Bump version to 6.1.0 and fix CHANGELOG (#348 )

Pattern guards for functions and switch statements (#339 )
* Add case guards to parser * Add pattern guards to infer types and fcode generation * Add functions guards * Add test for patterns guards * Update docs * Update CHANGELOG.md * Remove stateful context from Env for guards * Elaborate on guards * Add failing test for stateful pattern guards * Implement multiple guards * Fix tests * Disable aevm related tests * Split the sentence before if and otherwise * Fix type in docs * Implement multiple exprs in the same guard * Fix pretty printing * Change tests to include multiple guards * Add test for non-boolean guards * Desugar clauses with guards * Fix incomplete patterns bug * Fix docs * Compile to icode when no guards are used * Revert "Disable aevm related tests" This reverts commit e828099bd97dffe11438f2e48f3a92ce3641e85b.
2021-10-20 12:42:48 +03:00 · 2021-10-20 11:04:00 +03:00 · 2021-10-18 10:33:10 +02:00 · 2021-10-15 12:03:46 +02:00 · 2021-09-30 19:11:00 +02:00 · 2021-09-24 14:21:42 +02:00
50 changed files with 2591 additions and 1456 deletions
@@ -0,0 +1,7 @@
+import glob
+import shutil
+
+def pre_build(**kwargs):
+  for file in glob.glob('../docs/*.md'):
+    shutil.copy(file, 'docs')
+  shutil.copy('../CHANGELOG.md', 'docs')
@@ -0,0 +1,55 @@
+site_name: æternity Sophia Language
+plugins:
+  - search
+  - mkdocs-simple-hooks:
+      hooks:
+        on_pre_build: 'hook:pre_build'
+repo_url: 'https://github.com/aeternity/aesophia'
+edit_uri: ''
+
+extra:
+  version:
+    provider: mike
+
+theme:
+  favicon: favicon.png
+  name: material
+  custom_dir: overrides
+  language: en
+  palette:
+    - scheme: default
+      primary: pink
+      accent: pink
+      toggle:
+        icon: material/weather-night
+        name: Switch to dark mode
+    - scheme: slate
+      primary: pink
+      accent: pink
+      toggle:
+        icon: material/weather-sunny
+        name: Switch to light mode
+  features:
+    - content.tabs.link
+    - search.highlight
+    - search.share
+    - search.suggest
+
+  # Don't include MkDocs' JavaScript
+  include_search_page: false
+  search_index_only: true
+
+markdown_extensions:
+  - admonition
+  - pymdownx.highlight
+  - pymdownx.superfences
+  - toc:
+      toc_depth: 3
+
+nav:
+  - Introduction: index.md
+  - Syntax: sophia_syntax.md
+  - Features: sophia_features.md
+  - Standard library: sophia_stdlib.md
+  - Contract examples: sophia_examples.md
+  - Changelog: CHANGELOG.md
@@ -0,0 +1,8 @@
+{% extends "base.html" %}
+
+{% block outdated %}
+  You're not viewing the latest version.
+  <a href="{{ '../' ~ base_url }}">
+    <strong>Click here to go to latest.</strong>
+  </a>
+{% endblock %}
@@ -0,0 +1,25 @@
+name: Publish development docs
+on:
+  push:
+    branches: ['master']
+      
+jobs:
+  main:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-python@v2
+        with:
+          python-version: 3.8
+      - uses: actions/cache@v2
+        with:
+          path: ~/.cache/pip3
+          key: ${{ runner.os }}-pip-${{ hashFiles('.github/workflows/requirements.txt') }}
+      - run: pip3 install -r .github/workflows/requirements.txt
+      - run: git config --global user.email "github-action@users.noreply.github.com"
+      - run: git config --global user.name "GitHub Action"
+      - run: |
+          cd .docssite
+          mike deploy --push master
@@ -0,0 +1,26 @@
+name: Publish release docs
+on:
+  release:
+    types: [released]
+      
+jobs:
+  main:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-python@v2
+        with:
+          python-version: 3.8
+      - uses: actions/cache@v2
+        with:
+          path: ~/.cache/pip3
+          key: ${{ runner.os }}-pip-${{ hashFiles('.github/workflows/requirements.txt') }}
+      - run: pip3 install -r .github/workflows/requirements.txt
+      - run: git config --global user.email "github-action@users.noreply.github.com"
+      - run: git config --global user.name "GitHub Action"
+      - run: echo "RELEASE_VERSION=${GITHUB_REF:10}" >> $GITHUB_ENV
+      - run: |
+          cd .docssite
+          mike deploy --push --update-aliases $RELEASE_VERSION latest
@@ -0,0 +1,4 @@
+mkdocs==1.2.3
+mkdocs-simple-hooks==0.1.3
+mkdocs-material==7.1.9
+mike==1.0.1
@@ -22,3 +22,5 @@ aesophia
 .qcci
 current_counterexample.eqc
 test/contracts/test.aes
+__pycache__
+.docssite/docs/*.md
@@ -9,6 +9,29 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 ### Removed

+## [6.1.0] - 2021-10-20
+### Added
+- `Bitwise` stdlib
+- `Set` stdlib
+- `Option.force_msg`
+- Loading namespaces into the current scope (e.g. `using Pair`)
+- Assign patterns to variables (e.g. `let x::(t = y::_) = [1, 2, 3, 4]` where `t == [2, 3, 4]`)
+- Add builtin types (`AENS.name, AENS.pointee, Chain.ttl, Chain.base_tx, Chain.ga_meta_tx, Chain.paying_for_tx`) to
+  the calldata and result decoder
+- Patterns guards
+  ```
+  switch(x)
+    a::[] | a > 10 => 1
+    _              => 2
+  ```
+  ```
+  function
+    f(a::[]) | a > 10 = 1
+    f(_)              = 2
+  ```
+### Changed
+- Fixed the ACI renderer, it shouldn't drop the `stateful` modifier
+
 ## [6.0.2] 2021-07-05
 ### Changed
 - `List.from_to_step` now forbids non-positive step (this change does
@@ -309,7 +332,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Simplify calldata creation - instead of passing a compiled contract, simply
  pass a (stubbed) contract string.

-[Unreleased]: https://github.com/aeternity/aesophia/compare/v6.0.2...HEAD
+[Unreleased]: https://github.com/aeternity/aesophia/compare/v6.1.0...HEAD
+[6.1.0]: https://github.com/aeternity/aesophia/compare/v6.0.2...v6.1.0
 [6.0.2]: https://github.com/aeternity/aesophia/compare/v6.0.1...v6.0.2
 [6.0.1]: https://github.com/aeternity/aesophia/compare/v6.0.0...v6.0.1
 [6.0.0]: https://github.com/aeternity/aesophia/compare/v5.0.0...v6.0.0
@@ -1,6 +1,6 @@
 ISC License

-Copyright (c) 2017, aeternity developers
+Copyright (c) 2017, æternity developers

 Permission to use, copy, modify, and/or distribute this software for any
 purpose with or without fee is hereby granted, provided that the above
@@ -5,13 +5,17 @@ This is the __sophia__ compiler for the æternity system which compiles contract
 The compiler is currently being used three places
 - [The command line compiler](https://github.com/aeternity/aesophia_cli)
 - [The HTTP compiler](https://github.com/aeternity/aesophia_http)
- - In [Aeternity node](https://github.com/aeternity/aeternity) tests
+ - In [æternity node](https://github.com/aeternity/aeternity) tests

 ## Documentation

-* [Smart Contracts on aeternity Blockchain](https://github.com/aeternity/protocol/blob/master/contracts/contracts.md).
-* [Sophia Documentation](docs/sophia.md).
-* [Sophia Standard Library](docs/sophia_stdlib.md).
+* [Introduction](docs/index.md)
+* [Syntax](docs/sophia_syntax.md)
+* [Features](docs/sophia_features.md)
+* [Standard library](docs/sophia_stdlib.md)
+* [Contract examples](docs/sophia_examples.md)
+
+Additionally you can check out the [contracts section](https://github.com/aeternity/protocol/blob/master/contracts/contracts.md) of the æternity blockchain specification.

 ## Versioning

@@ -26,5 +30,5 @@ Versioning should follow the [semantic versioning](https://semver.org/spec/v2.0.

 The basic modules for interfacing the compiler:

-* [aeso_compiler: the Sophia compiler](./docs/aeso_compiler.md)
-* [aeso_aci: the ACI interface](./docs/aeso_aci.md)
+* [aeso_compiler: the Sophia compiler](docs/aeso_compiler.md)
+* [aeso_aci: the ACI interface](docs/aeso_aci.md)
@@ -0,0 +1,12 @@
+# Introduction
+Sophia is a functional language designed for smart contract development. It is strongly typed and has
+restricted mutable state.
+
+Sophia is customized for smart contracts, which can be published
+to a blockchain. Thus some features of conventional
+languages, such as floating point arithmetic, are not present in Sophia, and
+some [æternity blockchain](https://aeternity.com) specific primitives, constructions and types have been added.
+
+!!! Note
+    - For rapid prototyping of smart contracts check out [AEstudio](https://studio.aepps.com/)!
+    - For playing around and diving deeper into the language itself check out the [REPL](https://repl.aeternity.io/)!
@@ -0,0 +1,73 @@
+# Contract examples
+
+## Crowdfunding
+```sophia
+/*
+ * A simple crowd-funding example
+ */
+contract FundMe =
+
+  record spend_args = { recipient : address,
+                        amount    : int }
+
+  record state = { contributions : map(address, int),
+                   total         : int,
+                   beneficiary   : address,
+                   deadline      : int,
+                   goal          : int }
+
+  stateful function spend(args : spend_args) =
+    Chain.spend(args.recipient, args.amount)
+
+  entrypoint init(beneficiary, deadline, goal) : state =
+    { contributions = {},
+      beneficiary   = beneficiary,
+      deadline      = deadline,
+      total         = 0,
+      goal          = goal }
+
+  function is_contributor(addr) =
+    Map.member(addr, state.contributions)
+
+  stateful entrypoint contribute() =
+    if(Chain.block_height >= state.deadline)
+      spend({ recipient = Call.caller, amount = Call.value }) // Refund money
+      false
+    else
+      let amount =
+        switch(Map.lookup(Call.caller, state.contributions))
+          None    => Call.value
+          Some(n) => n + Call.value
+      put(state{ contributions[Call.caller] = amount,
+                 total @ tot = tot + Call.value })
+      true
+
+  stateful entrypoint withdraw() =
+    if(Chain.block_height < state.deadline)
+      abort("Cannot withdraw before deadline")
+    if(Call.caller == state.beneficiary)
+      withdraw_beneficiary()
+    elif(is_contributor(Call.caller))
+      withdraw_contributor()
+    else
+      abort("Not a contributor or beneficiary")
+
+  stateful function withdraw_beneficiary() =
+    require(state.total >= state.goal, "Project was not funded")
+    spend({recipient = state.beneficiary,
+           amount    = Contract.balance })
+
+  stateful function withdraw_contributor() =
+    if(state.total >= state.goal)
+      abort("Project was funded")
+    let to = Call.caller
+    spend({recipient = to,
+           amount    = state.contributions[to]})
+    put(state{ contributions @ c = Map.delete(to, c) })
+```
+
+## Repositories
+This is a list with repositories that include smart contracts written in Sophia:
+
+- [aepp-sophia-examples](https://github.com/aeternity/aepp-sophia-examples)
+    - A repository that contains lots of different examples. The functionality of these examples is - to some extent - also covered by tests written in JavaScript.
@@ -0,0 +1,877 @@
+# Features
+## Contracts
+
+The main unit of code in Sophia is the *contract*.
+
+- A contract implementation, or simply a contract, is the code for a
+  smart contract and consists of a list of types, entrypoints and local
+  functions. Only the entrypoints can be called from outside the contract.
+- A contract instance is an entity living on the block chain (or in a state
+  channel). Each instance has an address that can be used to call its
+  entrypoints, either from another contract or in a call transaction.
+- A contract may define a type `state` encapsulating its local
+  state. When creating a new contract the `init` entrypoint is executed and the
+  state is initialized to its return value.
+
+The language offers some primitive functions to interact with the blockchain and contracts.
+Please refer to the [Chain](sophia_stdlib.md#chain), [Contract](sophia_stdlib.md#contract)
+and the [Call](sophia_stdlib.md#call) namespaces in the documentation.
+
+### Calling other contracts
+
+To call a function in another contract you need the address to an instance of
+the contract. The type of the address must be a contract type, which consists
+of a number of type definitions and entrypoint declarations. For instance,
+
+```sophia
+// A contract type
+contract interface VotingType =
+  entrypoint vote : string => unit
+```
+
+Now given contract address of type `VotingType` you can call the `vote`
+entrypoint of that contract:
+
+```sophia
+contract VoteTwice =
+  entrypoint voteTwice(v : VotingType, alt : string) =
+    v.vote(alt)
+    v.vote(alt)
+```
+
+Contract calls take two optional named arguments `gas : int` and `value : int`
+that lets you set a gas limit and provide tokens to a contract call. If omitted
+the defaults are no gas limit and no tokens. Suppose there is a fee for voting:
+
+```sophia
+  entrypoint voteTwice(v : VotingType, fee : int, alt : string) =
+    v.vote(value = fee, alt)
+    v.vote(value = fee, alt)
+```
+
+Named arguments can be given in any order.
+
+Note that reentrant calls are not permitted. In other words, when calling
+another contract it cannot call you back (directly or indirectly).
+
+To construct a value of a contract type you can give a contract address literal
+(for instance `ct_2gPXZnZdKU716QBUFKaT4VdBZituK93KLvHJB3n4EnbrHHw4Ay`), or
+convert an account address to a contract address using `Address.to_contract`.
+Note that if the contract does not exist, or it doesn't have the entrypoint, or
+the type of the entrypoint does not match the stated contract type, the call
+fails.
+
+To recover the underlying `address` of a contract instance there is a field
+`address : address`. For instance, to send tokens to the voting contract (given that it is payable)
+without calling it you can write
+
+```sophia
+  entrypoint pay(v : VotingType, amount : int) =
+    Chain.spend(v.address, amount)
+```
+
+### Protected contract calls
+
+If a contract call fails for any reason (for instance, the remote contract
+crashes or runs out of gas, or the entrypoint doesn't exist or has the wrong
+type) the parent call also fails. To make it possible to recover from failures,
+contract calls takes a named argument `protected : bool` (default `false`).
+
+The protected argument must be a literal boolean, and when set to `true`
+changes the type of the contract call, wrapping the result in an `option` type.
+If the call fails the result is `None`, otherwise it's `Some(r)` where `r` is
+the return value of the call.
+
+```sophia
+contract interface VotingType =
+  entrypoint : vote : string => unit
+
+contract Voter =
+  entrypoint tryVote(v : VotingType, alt : string) =
+    switch(v.vote(alt, protected = true) : option(unit))
+      None    => "Voting failed"
+      Some(_) => "Voting successful"
+```
+
+Any gas that was consumed by the contract call before the failure stays
+consumed, which means that in order to protect against the remote contract
+running out of gas it is necessary to set a gas limit using the `gas` argument.
+However, note that errors that would normally consume all the gas in the
+transaction still only uses up the gas spent running the contract.
+
+
+### Contract factories and child contracts
+
+Since the version 6.0.0 Sophia supports deploying contracts by other
+contracts. This can be done in two ways:
+
+- Contract cloning via [`Chain.clone`](sophia_stdlib.md#clone)
+- Direct deploy via [`Chain.create`](sophia_stdlib.md#create)
+
+These functions take variable number of arguments that must match the created
+contract's `init` function. Beside that they take some additional named
+arguments – please refer to their documentation for the details.
+
+While `Chain.clone` requires only a `contract interface` and a living instance
+of a given contract on the chain, `Chain.create` needs a full definition of a
+to-create contract defined by the standard `contract` syntax, for example
+
+```sophia
+contract IntHolder =
+  type state = int
+  entrypoint init(x) = x
+  entrypoint get() = state
+
+main contract IntHolderFactory =
+  stateful entrypoint new(x : int) : IntHolder =
+    let ih = Chain.create(x) : IntHolder
+    ih
+```
+
+In case of a presence of child contracts (`IntHolder` in this case), the main
+contract must be pointed out with the `main` keyword as shown in the example.
+
+
+## Mutable state
+
+Sophia does not have arbitrary mutable state, but only a limited form of state
+associated with each contract instance.
+
+- Each contract defines a type `state` encapsulating its mutable state.
+  The type `state` defaults to the `unit`.
+- The initial state of a contract is computed by the contract's `init`
+  function. The `init` function is *pure* and returns the initial state as its
+  return value.
+  If the type `state` is `unit`, the `init` function defaults to returning the value `()`.
+  At contract creation time, the `init` function is executed and
+  its result is stored as the contract state.
+- The value of the state is accessible from inside the contract
+  through an implicitly bound variable `state`.
+- State updates are performed by calling a function `put : state => unit`.
+- Aside from the `put` function (and similar functions for transactions
+  and events), the language is purely functional.
+- Functions modifying the state need to be annotated with the `stateful` keyword (see below).
+
+To make it convenient to update parts of a deeply nested state Sophia
+provides special syntax for map/record updates.
+
+### Stateful functions
+
+Top-level functions and entrypoints must be annotated with the
+`stateful` keyword to be allowed to affect the state of the running contract.
+For instance,
+
+```sophia
+  stateful entrypoint set_state(s : state) =
+    put(s)
+```
+
+Without the `stateful` annotation the compiler does not allow the call to
+`put`. A `stateful` annotation is required to
+
+* Use a stateful primitive function. These are
+  - `put`
+  - `Chain.spend`
+  - `Oracle.register`
+  - `Oracle.query`
+  - `Oracle.respond`
+  - `Oracle.extend`
+  - `AENS.preclaim`
+  - `AENS.claim`
+  - `AENS.transfer`
+  - `AENS.revoke`
+  - `AENS.update`
+* Call a `stateful` function in the current contract
+* Call another contract with a non-zero `value` argument.
+
+A `stateful` annotation *is not* required to
+
+* Read the contract state.
+* Issue an event using the `event` function.
+* Call another contract with `value = 0`, even if the called function is stateful.
+
+## Payable
+
+### Payable contracts
+
+A concrete contract is by default *not* payable. Any attempt at spending to such
+a contract (either a `Chain.spend` or a normal spend transaction) will fail. If a
+contract shall be able to receive funds in this way it has to be declared `payable`:
+
+```sophia
+// A payable contract
+payable contract ExampleContract =
+  stateful entrypoint do_stuff() = ...
+```
+
+If in doubt, it is possible to check if an address is payable using
+`Address.is_payable(addr)`.
+
+### Payable entrypoints
+
+A contract entrypoint is by default *not* payable. Any call to such a function
+(either a [Remote call](#calling-other-contracts) or a contract call transaction)
+that has a non-zero `value` will fail. Contract entrypoints that should be called
+with a non-zero value should be declared `payable`.
+
+```sophia
+payable stateful entrypoint buy(to : address) =
+  if(Call.value > 42)
+    transfer_item(to)
+  else
+    abort("Value too low")
+```
+
+Note: In the æternity VM (AEVM) contracts and entrypoints were by default
+payable until the Lima release.
+
+## Namespaces
+
+Code can be split into libraries using the `namespace` construct. Namespaces
+can appear at the top-level and can contain type and function definitions, but
+not entrypoints. Outside the namespace you can refer to the (non-private) names
+by qualifying them with the namespace (`Namespace.name`).
+For example,
+
+```sophia
+namespace Library =
+  type number = int
+  function inc(x : number) : number = x + 1
+
+contract MyContract =
+  entrypoint plus2(x) : Library.number =
+    Library.inc(Library.inc(x))
+```
+
+Functions in namespaces have access to the same environment (including the
+`Chain`, `Call`, and `Contract`, builtin namespaces) as function in a contract,
+with the exception of `state`, `put` and `Chain.event` since these are
+dependent on the specific state and event types of the contract.
+
+To avoid mentioning the namespace every time it is used, Sophia allows
+including the namespace in the current scope with the `using` keyword:
+```
+include "Pair.aes"
+using Pair
+contract C =
+  type state = int
+  entrypoint init() =
+    let p = (1, 2)
+    fst(p)  // this is the same as Pair.fst(p)
+```
+
+It is also possible to make an alias for the namespace with the `as` keyword:
+```
+include "Pair.aes"
+contract C =
+  using Pair as P
+  type state = int
+  entrypoint init() =
+    let p = (1, 2)
+    P.fst(p)  // this is the same as Pair.fst(p)
+```
+
+Having the same alias for multiple namespaces is possible and it allows
+referening functions that are defined in different namespaces and have
+different names with the same alias:
+```
+namespace Xa = function f() = 1
+namespace Xb = function g() = 2
+contract Cntr =
+  using Xa as A
+  using Xb as A
+  type state = int
+  entrypoint init() = A.f() + A.g()
+```
+
+Note that using functions with the same name would result in an ambiguous name
+error:
+```
+namespace Xa = function f() = 1
+namespace Xb = function f() = 2
+contract Cntr =
+  using Xa as A
+  using Xb as A
+  type state = int
+
+  // the next line has an error because f is defined in both Xa and Xb
+  entrypoint init() = A.f()
+```
+
+Importing specific parts of a namespace or hiding these parts can also be
+done like this:
+```
+using Pair for [fst, snd]       // this will only import fst and snd
+using Triple hiding [fst, snd]  // this will import everything except for fst and snd
+```
+
+Note that it is possible to use a namespace in the top level of the file, in the
+contract level, namespace level, or in the function level.
+
+## Splitting code over multiple files
+
+Code from another file can be included in a contract using an `include`
+statement. These must appear at the top-level (outside the main contract). The
+included file can contain one or more namespaces and abstract contracts. For
+example, if the file `library.aes` contains
+
+```sophia
+namespace Library =
+  function inc(x) = x + 1
+```
+
+you can use it from another file using an `include`:
+
+```sophia
+include "library.aes"
+contract MyContract =
+  entrypoint plus2(x) = Library.inc(Library.inc(x))
+```
+
+This behaves as if the contents of `library.aes` was textually inserted into
+the file, except that error messages will refer to the original source
+locations. The language will try to include each file at most one time automatically,
+so even cyclic includes should be working without any special tinkering.
+
+## Standard library
+
+Sophia offers [standard library](sophia_stdlib.md) which exposes some
+primitive operations and some higher level utilities. The builtin
+namespaces like `Chain`, `Contract`, `Map`
+are included by default and are supported internally by the compiler.
+Others like `List`, `Frac`, `Option` need to be manually included using the
+`include` directive. For example
+```sophia
+include "List.aes"
+include "Pair.aes"
+-- Map is already there!
+
+namespace C =
+  entrypoint keys(m : map('a, 'b)) : list('a) =
+    List.map(Pair.fst, (Map.to_list(m)))
+```
+
+## Types
+Sophia has the following types:
+
+| Type                 | Description                                                                                 | Example                                                      |
+|----------------------|---------------------------------------------------------------------------------------------|--------------------------------------------------------------|
+| int                  | A 2-complement integer                                                                      | ```-1```                                                     |
+| address              | æternity address, 32 bytes                                                                 | ```Call.origin```                                            |
+| bool                 | A Boolean                                                                                   | ```true```                                                   |
+| bits                 | A bit field                                                                                 | ```Bits.none```                                              |
+| bytes(n)             | A byte array with `n` bytes                                                                 | ```#fedcba9876543210```                                      |
+| string               | An array of bytes                                                                           | ```"Foo"```                                                  |
+| list                 | A homogeneous immutable singly linked list.                                                 | ```[1, 2, 3]```                                              |
+| ('a, 'b) => 'c       | A function. Parentheses can be skipped if there is only one argument                        | ```(x : int, y : int) => x + y```                            |
+| tuple                | An ordered heterogeneous array                                                              | ```(42, "Foo", true)```                                      |
+| record               | An immutable key value store with fixed key names and typed values                          | ``` record balance = { owner: address, value: int } ```      |
+| map                  | An immutable key value store with dynamic mapping of keys of one type to values of one type | ```type accounts = map(string, address)```                   |
+| option('a)           | An optional value either None or Some('a)                                                   | ```Some(42)```                                               |
+| state                | A user defined type holding the contract state                                              | ```record state = { owner: address, magic_key: bytes(4) }``` |
+| event                | An append only list of blockchain events (or log entries)                                   | ```datatype event = EventX(indexed int, string)```           |
+| hash                 | A 32-byte hash - equivalent to `bytes(32)`                                                  |                                                              |
+| signature            | A signature - equivalent to `bytes(64)`                                                     |                                                              |
+| Chain.ttl            | Time-to-live (fixed height or relative to current block)                                    | ```FixedTTL(1050)``` ```RelativeTTL(50)```                   |
+| oracle('a, 'b)       | And oracle answering questions of type 'a with answers of type 'b                           | ```Oracle.register(acct, qfee, ttl)```                       |
+| oracle_query('a, 'b) | A specific oracle query                                                                     | ```Oracle.query(o, q, qfee, qttl, rttl)```                   |
+| contract             | A user defined, typed, contract address                                                     | ```function call_remote(r : RemoteContract) = r.fun()```     |
+
+## Literals
+| Type                 | Constant/Literal example(s)                                                                                                         |
+| ----------           | -------------------------------                                                                                                     |
+| int                  | `-1`, `2425`, `4598275923475723498573485768`                                                                                        |
+| address              | `ak_2gx9MEFxKvY9vMG5YnqnXWv1hCsX7rgnfvBLJS4aQurustR1rt`                                                                             |
+| bool                 | `true`, `false`                                                                                                                     |
+| bits                 | `Bits.none`, `Bits.all`                                                                                                             |
+| bytes(8)             | `#fedcba9876543210`                                                                                                                 |
+| string               | `"This is a string"`                                                                                                                |
+| list                 | `[1, 2, 3]`, `[(true, 24), (false, 19), (false, -42)]`                                                                              |
+| tuple                | `(42, "Foo", true)`                                                                                                                 |
+| record               | `{ owner = Call.origin, value = 100000000 }`                                                                                        |
+| map                  | `{["foo"] = 19, ["bar"] = 42}`, `{}`                                                                                                |
+| option(int)          | `Some(42)`, `None`                                                                                                                  |
+| state                | `state{ owner = Call.origin, magic_key = #a298105f }`                                                                               |
+| event                | `EventX(0, "Hello")`                                                                                                                |
+| hash                 | `#000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f`                                                                 |
+| signature            | `#000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f` |
+| Chain.ttl            | `FixedTTL(1050)`, `RelativeTTL(50)`                                                                                                 |
+| oracle('a, 'b)       | `ok_2YNyxd6TRJPNrTcEDCe9ra59SVUdp9FR9qWC5msKZWYD9bP9z5`                                                                             |
+| oracle_query('a, 'b) | `oq_2oRvyowJuJnEkxy58Ckkw77XfWJrmRgmGaLzhdqb67SKEL1gPY`                                                                             |
+| contract             | `ct_Ez6MyeTMm17YnTnDdHTSrzMEBKmy7Uz2sXu347bTDPgVH2ifJ`                                                                              |
+
+## Arithmetic
+
+Sophia integers (`int`) are represented by 256-bit (AEVM) or arbitrary-sized (FATE) signed words and supports the following
+arithmetic operations:
+- addition (`x + y`)
+- subtraction (`x - y`)
+- multiplication (`x * y`)
+- division (`x / y`), truncated towards zero
+- remainder (`x mod y`), satisfying `y * (x / y) + x mod y == x` for non-zero `y`
+- exponentiation (`x ^ y`)
+
+All operations are *safe* with respect to overflow and underflow. On AEVM they behave as the corresponding
+operations on arbitrary-size integers and fail with `arithmetic_error` if the
+result cannot be represented by a 256-bit signed word. For example, `2 ^ 255`
+fails rather than wrapping around to -2²⁵⁵.
+
+The division and modulo operations also throw an arithmetic error if the
+second argument is zero.
+
+## Bit fields
+
+Sophia integers do not support bit arithmetic. Instead there is a separate
+type `bits`. See the standard library [documentation](sophia_stdlib.md#bits).
+
+On the AEVM a bit field is represented by a 256-bit word and reading or writing
+a bit outside the 0..255 range fails with an `arithmetic_error`. On FATE a bit
+field can be of arbitrary size (but it is still represented by the
+corresponding integer, so setting very high bits can be expensive).
+
+## Type aliases
+
+Type aliases can be introduced with the `type` keyword and can be
+parameterized. For instance
+
+```sophia
+type number = int
+type string_map('a) = map(string, 'a)
+```
+
+A type alias and its definition can be used interchangeably. Sophia does not support
+higher-kinded types, meaning that following type alias is invalid: `type wrap('f, 'a) = 'f('a)`
+
+## Algebraic data types
+
+Sophia supports algebraic data types (variant types) and pattern matching. Data
+types are declared by giving a list of constructors with
+their respective arguments. For instance,
+
+```sophia
+datatype one_or_both('a, 'b) = Left('a) | Right('b) | Both('a, 'b)
+```
+
+Elements of data types can be pattern matched against, using the `switch` construct:
+
+```sophia
+function get_left(x : one_or_both('a, 'b)) : option('a) =
+  switch(x)
+    Left(x)    => Some(x)
+    Right(_)   => None
+    Both(x, _) => Some(x)
+```
+
+or directly in the left-hand side:
+```sophia
+function
+  get_left : one_or_both('a, 'b) => option('a)
+  get_left(Left(x))    = Some(x)
+  get_left(Right(_))   = None
+  get_left(Both(x, _)) = Some(x)
+```
+
+*NOTE: Data types cannot currently be recursive.*
+
+Sophia also supports the assignment of patterns to variables:
+```sophia
+function f(x) = switch(x)
+  h1::(t = h2::_) => (h1 + h2)::t  // same as `h1::h2::k => (h1 + h2)::h2::k`
+  _ => x
+
+function g(p : int * option(int)) : int =
+  let (a, (o = Some(b))) = p  // o is equal to Pair.snd(p)
+  b
+```
+
+Guards are boolean expressions that can be used on patterns in both switch
+statements and functions definitions. If a guard expression evaluates to
+`true`, then the corresponding body will be used. Otherwise, the next pattern
+will be checked:
+
+```sophia
+function get_left_if_positive(x : one_or_both(int, 'b)) : option(int) =
+  switch(x)
+    Left(x)    | x > 0 => Some(x)
+    Both(x, _) | x > 0 => Some(x)
+    _                  => None
+```
+
+```sophia
+function
+  get_left_if_positive : one_or_both(int, 'b) => option(int)
+  get_left_if_positive(Left(x))    | x > 0 = Some(x)
+  get_left_if_positive(Both(x, _)) | x > 0 = Some(x)
+  get_left_if_positive(_)                  = None
+```
+
+Guards cannot be stateful even when used inside a stateful function.
+
+## Lists
+
+A Sophia list is a dynamically sized, homogenous, immutable, singly
+linked list. A list is constructed with the syntax `[1, 2, 3]`. The
+elements of a list can be any of datatype but they must have the same
+type. The type of lists with elements of type `'e` is written
+`list('e)`. For example we can have the following lists:
+
+```sophia
+[1, 33, 2, 666]                                                   : list(int)
+[(1, "aaa"), (10, "jjj"), (666, "the beast")]                     : list(int * string)
+[{[1] = "aaa", [10] = "jjj"}, {[5] = "eee", [666] = "the beast"}] : list(map(int, string))
+```
+
+New elements can be prepended to the front of a list with the `::`
+operator. So `42 :: [1, 2, 3]` returns the list `[42, 1, 2, 3]`. The
+concatenation operator `++` appends its second argument to its first
+and returns the resulting list. So concatenating two lists
+`[1, 22, 33] ++ [10, 18, 55]` returns the list `[1, 22, 33, 10, 18, 55]`.
+
+Sophia supports list comprehensions known from languages like Python, Haskell or Erlang.
+Example syntax:
+```sophia
+[x + y | x <- [1,2,3,4,5], let k = x*x, if (k > 5), y <- [k, k+1, k+2]]
+// yields [12,13,14,20,21,22,30,31,32]
+```
+
+Lists can be constructed using the range syntax using special `..` operator:
+```sophia
+[1..4] == [1,2,3,4]
+```
+The ranges are always ascending and have step equal to 1.
+
+
+Please refer to the [standard library](sophia_stdlib.md#list) for the predefined functionalities.
+
+## Maps and records
+
+A Sophia record type is given by a fixed set of fields with associated,
+possibly different, types. For instance
+```sophia
+  record account = { name    : string,
+                     balance : int,
+                     history : list(transaction) }
+```
+
+Maps, on the other hand, can contain an arbitrary number of key-value bindings,
+but of a fixed type. The type of maps with keys of type `'k` and values of type
+`'v` is written `map('k, 'v)`. The key type can be any type that does not
+contain a map or a function type.
+
+Please refer to the [standard library](sophia_stdlib.md#map) for the predefined functionalities.
+
+### Constructing maps and records
+
+A value of record type is constructed by giving a value for each of the fields.
+For the example above,
+```sophia
+  function new_account(name) =
+    {name = name, balance = 0, history = []}
+```
+Maps are constructed similarly, with keys enclosed in square brackets
+```sophia
+  function example_map() : map(string, int) =
+    {["key1"] = 1, ["key2"] = 2}
+```
+The empty map is written `{}`.
+
+### Accessing values
+
+Record fields access is written `r.f` and map lookup `m[k]`. For instance,
+```sophia
+  function get_balance(a : address, accounts : map(address, account)) =
+    accounts[a].balance
+```
+Looking up a non-existing key in a map results in contract execution failing. A
+default value to return for non-existing keys can be provided using the syntax
+`m[k = default]`. See also `Map.member` and `Map.lookup` below.
+
+### Updating a value
+
+Record field updates are written `r{f = v}`. This creates a new record value
+which is the same as `r`, but with the value of the field `f` replaced by `v`.
+Similarly, `m{[k] = v}` constructs a map with the same values as `m` except
+that `k` maps to `v`. It makes no difference if `m` has a mapping for `k` or
+not.
+
+It is possible to give a name to the old value of a field or mapping in an
+update: instead of `acc{ balance = acc.balance + 100 }` it is possible to write
+`acc{ balance @ b = b + 100 }`, binding `b` to `acc.balance`. When giving a
+name to a map value (`m{ [k] @ x = v }`), the corresponding key must be present
+in the map or execution fails, but a default value can be provided:
+`m{ [k = default] @ x = v }`. In this case `x` is bound to `default` if
+`k` is not in the map.
+
+Updates can be nested:
+```sophia
+function clear_history(a : address, accounts : map(address, account)) : map(address, account) =
+  accounts{ [a].history = [] }
+```
+This is equivalent to `accounts{ [a] @ acc = acc{ history = [] } }` and thus
+requires `a` to be present in the accounts map. To have `clear_history` create
+an account if `a` is not in the map you can write (given a function `empty_account`):
+```sophia
+  accounts{ [a = empty_account()].history = [] }
+```
+
+### Map implementation
+
+Internally in the VM maps are implemented as hash maps and support fast lookup
+and update. Large maps can be stored in the contract state and the size of the
+map does not contribute to the gas costs of a contract call reading or updating
+it.
+
+## Strings
+
+There is a builtin type `string`, which can be seen as an array of bytes.
+Strings can be compared for equality (`==`, `!=`), used as keys in maps and
+records, and used in builtin functions `String.length`, `String.concat` and
+the hash functions described below.
+
+Please refer to the `String` [library documentation](sophia_stdlib.md#string).
+
+## Chars
+
+There is a builtin type `char` (the underlying representation being an integer),
+mainly used to manipulate strings via `String.to_list`/`String.from_list`.
+
+Characters can also be introduced as character literals (`'x', '+', ...).
+
+Please refer to the `Char` [library documentation](sophia_stdlib.md#char).
+
+## Byte arrays
+
+Byte arrays are fixed size arrays of 8-bit integers. They are described in hexadecimal system,
+for example the literal `#cafe` creates a two-element array of bytes `ca` (202) and `fe` (254)
+and thus is a value of type `bytes(2)`.
+
+Please refer to the `Bytes` [library documentation](sophia_stdlib.md#bytes).
+
+## Cryptographic builtins
+
+Libraries [Crypto](sophia_stdlib.md#crypto) and [String](sophia_stdlib.md#string) provide functions to
+hash objects, verify signatures etc. The `hash` is a type alias for `bytes(32)`.
+
+## Authorization interface
+
+When a Generalized account is authorized, the authorization function needs
+access to the transaction and the transaction hash for the wrapped transaction. (A `GAMetaTx`
+wrapping a transaction.) The transaction and the transaction hash is available in the primitive
+`Auth.tx` and `Auth.tx_hash` respectively, they are *only* available during authentication if invoked by a
+normal contract call they return `None`.
+
+## Oracle interface
+You can attach an oracle to the current contract and you can interact with oracles
+through the Oracle interface.
+
+For a full description of how Oracle works see
+[Oracles](https://github.com/aeternity/protocol/blob/master/oracles/oracles.md#oracles).
+For a functionality documentation refer to the [standard library](sophia_stdlib.md#oracle).
+
+### Example
+
+Example for an oracle answering questions of type `string` with answers of type `int`:
+```sophia
+contract Oracles =
+
+  stateful entrypoint registerOracle(acct : address,
+                                     sign : signature,   // Signed network id + oracle address + contract address
+                                     qfee : int,
+                                     ttl  : Chain.ttl) : oracle(string, int) =
+     Oracle.register(acct, signature = sign, qfee, ttl)
+
+  entrypoint queryFee(o : oracle(string, int)) : int =
+    Oracle.query_fee(o)
+
+  payable stateful entrypoint createQuery(o    : oracle_query(string, int),
+                                          q    : string,
+                                          qfee : int,
+                                          qttl : Chain.ttl,
+                                          rttl : int) : oracle_query(string, int) =
+    require(qfee =< Call.value, "insufficient value for qfee")
+    Oracle.query(o, q, qfee, qttl, RelativeTTL(rttl))
+
+  stateful entrypoint extendOracle(o   : oracle(string, int),
+                                   ttl : Chain.ttl) : unit =
+    Oracle.extend(o, ttl)
+
+  stateful entrypoint signExtendOracle(o    : oracle(string, int),
+                                       sign : signature,   // Signed network id + oracle address + contract address
+                                       ttl  : Chain.ttl) : unit =
+    Oracle.extend(o, signature = sign, ttl)
+
+  stateful entrypoint respond(o    : oracle(string, int),
+                              q    : oracle_query(string, int),
+                              sign : signature,        // Signed network id + oracle query id + contract address
+                              r    : int) =
+    Oracle.respond(o, q, signature = sign, r)
+
+  entrypoint getQuestion(o : oracle(string, int),
+                         q : oracle_query(string, int)) : string =
+    Oracle.get_question(o, q)
+
+  entrypoint hasAnswer(o : oracle(string, int),
+                       q : oracle_query(string, int)) =
+    switch(Oracle.get_answer(o, q))
+      None    => false
+      Some(_) => true
+
+  entrypoint getAnswer(o : oracle(string, int),
+                       q : oracle_query(string, int)) : option(int) =
+    Oracle.get_answer(o, q)
+```
+
+### Sanity checks
+
+When an Oracle literal is passed to a contract, no deep checks are performed.
+For extra safety [Oracle.check](sophia_stdlib.md#check) and [Oracle.check_query](sophia_stdlib.md#check_query)
+functions are provided.
+
+## AENS interface
+
+Contracts can interact with the
+[æternity naming system](https://github.com/aeternity/protocol/blob/master/AENS.md).
+For this purpose the [AENS](sophia_stdlib.md#aens) library was exposed.
+
+### Example
+
+In this example we assume that the name `name` already exists, and is owned by
+an account with address `addr`. In order to allow a contract `ct` to handle
+`name` the account holder needs to create a
+[signature](#delegation-signature) `sig` of `addr | name.hash | ct.address`.
+
+Armed with this information we can for example write a function that extends
+the name if it expires within 1000 blocks:
+```sophia
+  stateful entrypoint extend_if_necessary(addr : address, name : string, sig : signature) =
+    switch(AENS.lookup(name))
+      None => ()
+      Some(AENS.Name(_, FixedTTL(expiry), _)) =>
+        if(Chain.block_height + 1000 > expiry)
+          AENS.update(addr, name, Some(RelativeTTL(50000)), None, None, signature = sig)
+```
+
+And we can write functions that adds and removes keys from the pointers of the
+name:
+```sophia
+  stateful entrypoint add_key(addr : address, name : string, key : string,
+                              pt : AENS.pointee, sig : signature) =
+    switch(AENS.lookup(name))
+      None => ()
+      Some(AENS.Name(_, _, ptrs)) =>
+        AENS.update(addr, name, None, None, Some(ptrs{[key] = pt}), signature = sig)
+
+  stateful entrypoint delete_key(addr : address, name : string,
+                                 key : string, sig : signature) =
+    switch(AENS.lookup(name))
+      None => ()
+      Some(AENS.Name(_, _, ptrs)) =>
+        let ptrs = Map.delete(key, ptrs)
+        AENS.update(addr, name, None, None, Some(ptrs), signature = sig)
+```
+
+*Note:* From the Iris hardfork more strict rules apply for AENS pointers, when
+a Sophia contract lookup or update (bad) legacy pointers, the bad keys are
+automatically removed so they will not appear in the pointers map.
+
+## Events
+
+Sophia contracts log structured messages to an event log in the resulting
+blockchain transaction. The event log is quite similar to [Events in
+Solidity](https://solidity.readthedocs.io/en/v0.4.24/contracts.html#events).
+Events are further discussed in the [protocol](https://github.com/aeternity/protocol/blob/master/contracts/events.md).
+
+
+To use events a contract must declare a datatype `event`, and events are then
+logged using the `Chain.event` function:
+
+```sophia
+  datatype event
+    = Event1(int, int, string)
+    | Event2(string, address)
+
+  Chain.event(e : event) : unit
+```
+
+The event can have 0-3 *indexed* fields, and an optional *payload* field. A
+field is indexed if it fits in a 32-byte word, i.e.
+- `bool`
+- `int`
+- `bits`
+- `address`
+- `oracle(_, _)`
+- `oracle_query(_, _)`
+- contract types
+- `bytes(n)` for `n` ≤ 32, in particular `hash`
+
+The payload field must be either a string or a byte array of more than 32 bytes.
+The fields can appear in any order.
+
+*NOTE:* Indexing is not part of the core æternity node.
+
+Events are emitted by using the `Chain.event` function. The following function
+will emit one Event of each kind in the example.
+
+```sophia
+  entrypoint emit_events() : () =
+    Chain.event(Event1(42, 34, "foo"))
+    Chain.event(Event2("This is not indexed", Contract.address))
+```
+
+### Argument order
+
+It is only possible to have one (1) `string` parameter in the event, but it can
+be placed in any position (and its value will end up in the `data` field), i.e.
+```sophia
+AnotherEvent(string, indexed address)
+
+...
+
+Chain.event(AnotherEvent("This is not indexed", Contract.address))
+```
+would yield exactly the same result in the example above!
+
+## Compiler pragmas
+
+To enforce that a contract is only compiled with specific versions of the
+Sophia compiler, you can give one or more `@compiler` pragmas at the
+top-level (typically at the beginning) of a file. For instance, to enforce that
+a contract is compiled with version 4.3 of the compiler you write
+
+```sophia
+@compiler >= 4.3
+@compiler <  4.4
+```
+
+Valid operators in compiler pragmas are `<`, `=<`, `==`, `>=`, and `>`. Version
+numbers are given as a sequence of non-negative integers separated by dots.
+Trailing zeros are ignored, so `4.0.0 == 4`. If a constraint is violated an
+error is reported and compilation fails.
+
+## Exceptions
+
+Contracts can fail with an (uncatchable) exception using the built-in function
+
+```sophia
+abort(reason : string) : 'a
+```
+
+Calling abort causes the top-level call transaction to return an error result
+containing the `reason` string. Only the gas used up to and including the abort
+call is charged. This is different from termination due to a crash which
+consumes all available gas.
+
+For convenience the following function is also built-in:
+
+```sophia
+function require(b : bool, err : string) =
+    if(!b) abort(err)
+```
+
+## Delegation signature
+
+Some chain operations (`Oracle.<operation>` and `AENS.<operation>`) have an
+optional delegation signature. This is typically used when a user/accounts
+would like to allow a contract to act on it's behalf. The exact data to be
+signed varies for the different operations, but in all cases you should prepend
+the signature data with the `network_id` (`ae_mainnet` for the æternity mainnet, etc.).
@@ -0,0 +1,263 @@
+# Syntax
+
+## Lexical syntax
+
+### Comments
+
+Single line comments start with `//` and block comments are enclosed in `/*`
+and `*/` and can be nested.
+
+### Keywords
+
+```
+contract elif else entrypoint false function if import include let mod namespace
+private payable stateful switch true type record datatype main interface
+```
+
+### Tokens
+
+- `Id = [a-z_][A-Za-z0-9_']*` identifiers start with a lower case letter.
+- `Con = [A-Z][A-Za-z0-9_']*` constructors start with an upper case letter.
+- `QId = (Con\.)+Id` qualified identifiers (e.g. `Map.member`)
+- `QCon = (Con\.)+Con` qualified constructor
+- `TVar = 'Id` type variable (e.g `'a`, `'b`)
+- `Int = [0-9]+(_[0-9]+)*|0x[0-9A-Fa-f]+(_[0-9A-Fa-f]+)*` integer literal with optional `_` separators
+- `Bytes = #[0-9A-Fa-f]+(_[0-9A-Fa-f]+)*` byte array literal with optional `_` separators
+- `String` string literal enclosed in `"` with escape character `\`
+- `Char` character literal enclosed in `'` with escape character `\`
+- `AccountAddress` base58-encoded 32 byte account pubkey with `ak_` prefix
+- `ContractAddress` base58-encoded 32 byte contract address with `ct_` prefix
+- `OracleAddress` base58-encoded 32 byte oracle address with `ok_` prefix
+- `OracleQueryId` base58-encoded 32 byte oracle query id with `oq_` prefix
+
+Valid string escape codes are
+
+| Escape        |       ASCII |   |
+|---------------|-------------|---|
+| `\b`          |           8 |   |
+| `\t`          |           9 |   |
+| `\n`          |          10 |   |
+| `\v`          |          11 |   |
+| `\f`          |          12 |   |
+| `\r`          |          13 |   |
+| `\e`          |          27 |   |
+| `\xHexDigits` | *HexDigits* |   |
+
+
+See the [identifier encoding scheme](https://github.com/aeternity/protocol/blob/master/node/api/api_encoding.md) for the
+details on the base58 literals.
+
+## Layout blocks
+
+Sophia uses Python-style layout rules to group declarations and statements. A
+layout block with more than one element must start on a separate line and be
+indented more than the currently enclosing layout block. Blocks with a single
+element can be written on the same line as the previous token.
+
+Each element of the block must share the same indentation and no part of an
+element may be indented less than the indentation of the block. For instance
+
+```sophia
+contract Layout =
+  function foo() = 0  // no layout
+  function bar() =    // layout block starts on next line
+    let x = foo()     // indented more than 2 spaces
+    x
+     + 1              // the '+' is indented more than the 'x'
+```
+
+## Notation
+
+In describing the syntax below, we use the following conventions:
+
+- Upper-case identifiers denote non-terminals (like `Expr`) or terminals with
+  some associated value (like `Id`).
+- Keywords and symbols are enclosed in single quotes: `'let'` or `'='`.
+- Choices are separated by vertical bars: `|`.
+- Optional elements are enclosed in `[` square brackets `]`.
+- `(` Parentheses `)` are used for grouping.
+- Zero or more repetitions are denoted by a postfix `*`, and one or more
+  repetitions by a `+`.
+- `Block(X)` denotes a layout block of `X`s.
+- `Sep(X, S)` is short for `[X (S X)*]`, i.e. a possibly empty sequence of `X`s
+  separated by `S`s.
+- `Sep1(X, S)` is short for `X (S X)*`, i.e. same as `Sep`, but must not be empty.
+
+
+## Declarations
+
+A Sophia file consists of a sequence of *declarations* in a layout block.
+
+```c
+File ::= Block(TopDecl)
+
+TopDecl ::= ['payable'] 'contract' Con '=' Block(Decl)
+       | 'namespace' Con '=' Block(Decl)
+       | '@compiler' PragmaOp Version
+       | 'include' String
+
+Decl ::= 'type'     Id ['(' TVar* ')'] '=' TypeAlias
+       | 'record'   Id ['(' TVar* ')'] '=' RecordType
+       | 'datatype' Id ['(' TVar* ')'] '=' DataType
+       | (EModifier* 'entrypoint' | FModifier* 'function') Block(FunDecl)
+
+FunDecl ::= Id ':' Type                             // Type signature
+          | Id Args [':' Type] '=' Block(Stmt)      // Definition
+
+PragmaOp ::= '<' | '=<' | '==' | '>=' | '>'
+Version  ::= Sep1(Int, '.')
+
+EModifier ::= 'payable' | 'stateful'
+FModifier ::= 'stateful' | 'private'
+
+Args ::= '(' Sep(Pattern, ',') ')'
+```
+
+Contract declarations must appear at the top-level.
+
+For example,
+```sophia
+contract Test =
+  type t = int
+  entrypoint add (x : t, y : t) = x + y
+```
+
+There are three forms of type declarations: type aliases (declared with the
+`type` keyword), record type definitions (`record`) and data type definitions
+(`datatype`):
+
+```c
+TypeAlias  ::= Type
+RecordType ::= '{' Sep(FieldType, ',') '}'
+DataType   ::= Sep1(ConDecl, '|')
+
+FieldType  ::= Id ':' Type
+ConDecl    ::= Con ['(' Sep1(Type, ',') ')']
+```
+
+For example,
+```sophia
+record   point('a) = {x : 'a, y : 'a}
+datatype shape('a) = Circle(point('a), 'a) | Rect(point('a), point('a))
+type     int_shape = shape(int)
+```
+
+## Types
+
+```c
+Type ::= Domain '=>' Type             // Function type
+       | Type '(' Sep(Type, ',') ')'  // Type application
+       | '(' Type ')'                 // Parens
+       | 'unit' | Sep(Type, '*')      // Tuples
+       | Id | QId | TVar
+
+Domain ::= Type                       // Single argument
+         | '(' Sep(Type, ',') ')'     // Multiple arguments
+```
+
+The function type arrow associates to the right.
+
+Example,
+```sophia
+'a => list('a) => (int * list('a))
+```
+
+## Statements
+
+Function bodies are blocks of *statements*, where a statement is one of the following
+
+```c
+Stmt ::= 'switch' '(' Expr ')' Block(Case)
+       | 'if' '(' Expr ')' Block(Stmt)
+       | 'elif' '(' Expr ')' Block(Stmt)
+       | 'else' Block(Stmt)
+       | 'let' LetDef
+       | Expr
+
+LetDef ::= Id Args [':' Type] '=' Block(Stmt)   // Function definition
+         | Pattern '=' Block(Stmt)              // Value definition
+
+Case    ::= Pattern '=>' Block(Stmt)
+Pattern ::= Expr
+```
+
+`if` statements can be followed by zero or more `elif` statements and an optional final `else` statement. For example,
+
+```sophia
+let x : int = 4
+switch(f(x))
+  None => 0
+  Some(y) =>
+    if(y > 10)
+      "too big"
+    elif(y < 3)
+      "too small"
+    else
+      "just right"
+```
+
+## Expressions
+
+```c
+Expr ::= '(' LamArgs ')' '=>' Block(Stmt)   // Anonymous function    (x) => x + 1
+       | 'if' '(' Expr ')' Expr 'else' Expr // If expression         if(x < y) y else x
+       | Expr ':' Type                      // Type annotation       5 : int
+       | Expr BinOp Expr                    // Binary operator       x + y
+       | UnOp Expr                          // Unary operator        ! b
+       | Expr '(' Sep(Expr, ',') ')'        // Application           f(x, y)
+       | Expr '.' Id                        // Projection            state.x
+       | Expr '[' Expr ']'                  // Map lookup            map[key]
+       | Expr '{' Sep(FieldUpdate, ',') '}' // Record or map update  r{ fld[key].x = y }
+       | '[' Sep(Expr, ',') ']'             // List                  [1, 2, 3]
+       | '[' Expr '|' Sep(Generator, ',') ']'
+                                            // List comprehension    [k | x <- [1], if (f(x)), let k = x+1]
+       | '[' Expr '..' Expr ']'             // List range            [1..n]
+       | '{' Sep(FieldUpdate, ',') '}'      // Record or map value   {x = 0, y = 1}, {[key] = val}
+       | '(' Expr ')'                       // Parens                (1 + 2) * 3
+       | Id | Con | QId | QCon              // Identifiers           x, None, Map.member, AELib.Token
+       | Int | Bytes | String | Char        // Literals              123, 0xff, #00abc123, "foo", '%'
+       | AccountAddress | ContractAddress   // Chain identifiers
+       | OracleAddress | OracleQueryId      // Chain identifiers
+
+Generator ::= Pattern '<-' Expr   // Generator
+            | 'if' '(' Expr ')'   // Guard
+            | LetDef              // Definition
+
+LamArgs ::= '(' Sep(LamArg, ',') ')'
+LamArg  ::= Id [':' Type]
+
+FieldUpdate ::= Path '=' Expr
+Path ::= Id                 // Record field
+       | '[' Expr ']'       // Map key
+       | Path '.' Id        // Nested record field
+       | Path '[' Expr ']'  // Nested map key
+
+BinOp ::= '||' | '&&' | '<' | '>' | '=<' | '>=' | '==' | '!='
+        | '::' | '++' | '+' | '-' | '*' | '/' | 'mod' | '^'
+UnOp  ::= '-' | '!'
+```
+
+## Operators types
+
+| Operators | Type
+| --- | ---
+| `-` `+` `*` `/` `mod` `^` | arithmetic operators
+| `!` `&&` `\|\|` | logical operators
+| `==` `!=` `<` `>` `=<` `>=` | comparison operators
+| `::` `++` | list operators
+
+## Operator precendences
+
+In order of highest to lowest precedence.
+
+| Operators | Associativity
+| --- | ---
+| `!` | right
+| `^` | left
+| `*` `/` `mod` | left
+| `-` (unary) | right
+| `+` `-` | left
+| `::` `++` | right
+| `<` `>` `=<` `>=` `==` `!=` | none
+| `&&` | right
+| `\|\|` | right
@@ -0,0 +1,136 @@
+@compiler >= 4.3
+
+namespace Bitwise =
+
+  // bit shift 'x' right 'n' postions
+  function bsr(n : int, x : int) : int =
+    let step = 2^n
+    let res  = x / step
+    if (x >= 0 || x mod step == 0)
+      res
+    else
+      res - 1
+
+  // bit shift 'x' left 'n' positions
+  function bsl(n : int, x : int) : int =
+    x * 2^n
+
+  // bit shift 'x' left 'n' positions, limit at 'lim' bits
+  function bsli(n : int, x : int, lim : int) : int =
+    (x * 2^n) mod (2^lim)
+
+  // bitwise 'and' for arbitrary precision integers
+  function band(a : int, b : int) : int =
+      if (a >= 0 && b >= 0)
+        uband_(a, b)
+      elif (b >= 0)
+        ubnand_(b, -1 - a)
+      elif (a >= 0)
+        ubnand_(a, -1 - b)
+      else
+        -1 - ubor_(-1 - a, -1 - b)
+
+  // bitwise 'or' for arbitrary precision integers
+  function
+    bor : (int, int) => int
+    bor(0, b) = b
+    bor(a, 0) = a
+    bor(a : int, b : int) : int =
+      if (a >= 0 && b >= 0)
+        ubor_(a, b)
+      elif (b >= 0)
+        -1 - ubnand_(-1 - a, b)
+      elif (a >= 0)
+        -1 - ubnand_(-1 - b, a)
+      else
+        -1 - uband_(-1 - a, -1 - b)
+
+  // bitwise 'xor' for arbitrary precision integers
+  function
+    bxor : (int, int) => int
+    bxor(0, b) = b
+    bxor(a, 0) = a
+    bxor(a, b) =
+      if (a >= 0 && b >= 0)
+        ubxor_(a, b)
+      elif (b >= 0)
+        -1 - ubxor_(-1 - a, b)
+      elif (a >= 0)
+        -1 - ubxor_(a, -1 - b)
+      else
+        ubxor_(-1 - a, -1 - b)
+
+  // bitwise 'not' for arbitrary precision integers
+  function bnot(a : int) = bxor(a, -1)
+
+  // Bitwise 'and' for non-negative integers
+  function uband(a : int, b : int) : int =
+    require(a >= 0 && b >= 0, "uband is only defined for non-negative integers")
+    switch((a, b))
+      (0, _) => 0
+      (_, 0) => 0
+      _      => uband__(a, b, 1, 0)
+
+  private function uband_(a, b) = uband__(a, b, 1, 0)
+
+  private function
+    uband__(0, b, val, acc) = acc
+    uband__(a, 0, val, acc) = acc
+    uband__(a, b, val, acc) =
+      switch (a mod 2 + b mod 2)
+        2 => uband__(a / 2, b / 2, val * 2, acc + val)
+        _ => uband__(a / 2, b / 2, val * 2, acc)
+
+  // Bitwise 'or' for non-negative integers
+  function ubor(a, b) =
+    require(a >= 0 && b >= 0, "ubor is only defined for non-negative integers")
+    switch((a, b))
+      (0, _) => b
+      (_, 0) => a
+      _      => ubor__(a, b, 1, 0)
+
+  private function ubor_(a, b) = ubor__(a, b, 1, 0)
+
+  private function
+    ubor__(0, 0, val, acc) = acc
+    ubor__(a, b, val, acc) =
+      switch (a mod 2 + b mod 2)
+        0 => ubor__(a / 2, b / 2, val * 2, acc)
+        _ => ubor__(a / 2, b / 2, val * 2, acc + val)
+
+  //Bitwise 'xor' for non-negative integers
+  function
+    ubxor : (int, int) => int
+    ubxor(0, b) = b
+    ubxor(a, 0) = a
+    ubxor(a, b) =
+      require(a >= 0 && b >= 0, "ubxor is only defined for non-negative integers")
+      ubxor__(a, b, 1, 0)
+
+  private function ubxor_(a, b) = ubxor__(a, b, 1, 0)
+
+  private function
+    ubxor__(0, 0, val, acc) = acc
+    ubxor__(a, b, val, acc) =
+      switch(a mod 2 + b mod 2)
+        1 => ubxor__(a / 2, b / 2, val * 2, acc + val)
+        _ => ubxor__(a / 2, b / 2, val * 2, acc)
+
+  // Bitwise combined 'and' and 'not' of second argument for positive integers
+  // x 'bnand' y = x 'band' ('bnot' y)
+  // The tricky bit is that after negation the second argument has an infinite number of 1's
+  // use as many as needed!
+  //
+  // NOTE: this function is not symmetric!
+  private function ubnand(a, b) =
+    require(a >= 0 && b >= 0, "ubxor is only defined for non-negative integers")
+    ubnand__(a, b, 1, 0)
+
+  private function ubnand_(a, b) = ubnand__(a, b, 1, 0)
+
+  private function
+    ubnand__(0, b, val, acc) = acc
+    ubnand__(a, b, val, acc) =
+      switch((a mod 2, b mod 2))
+        (1, 0) => ubnand__(a / 2, b / 2, val * 2, acc + val)
+        _      => ubnand__(a / 2, b / 2, val * 2, acc)
@@ -26,6 +26,12 @@ namespace Option =
    None    => abort("Forced None value")
    Some(x) => x

+/** Assume it is `Some` with custom error message
+ */
+  function force_msg(o : option('a), err : string) : 'a = switch(o)
+    None    => abort(err)
+    Some(x) => x
+
  function contains(e : 'a, o : option('a)) = o == Some(e)

  function on_elem(o : option('a), f : 'a => unit) : unit = match((), f, o)
@@ -0,0 +1,51 @@
+include "List.aes"
+include "Option.aes"
+include "Pair.aes"
+
+namespace Set =
+  record set('a) = { to_map : map('a, unit) }
+
+  function new() : set('a) =
+    { to_map = {} }
+
+  function member(e : 'a, s : set('a)) : bool =
+    Map.member(e, s.to_map)
+
+  function insert(e : 'a, s : set('a)) : set('a) =
+    { to_map = s.to_map{[e] = ()} }
+
+  function delete(e : 'a, s : set('a)) : set('a) =
+    { to_map = Map.delete(e, s.to_map) }
+
+  function size(s : set('a)) : int =
+    Map.size(s.to_map)
+
+  function to_list(s : set('a)) : list('a) =
+    List.map(Pair.fst, Map.to_list(s.to_map))
+
+  function from_list(l : list('a)) : set('a) =
+    { to_map = Map.from_list(List.map((x) => (x, ()), l)) }
+
+  function filter(p : 'a => bool, s : set('a)) : set('a) =
+    from_list(List.filter(p, to_list(s)))
+
+  function fold(f : ('a, 'b) => 'b, acc : 'b, s : set('a)) : 'b =
+    List.foldr(f, acc, to_list(s))
+
+  function subtract(s1 : set('a), s2 : set('a)) : set('a) =
+    filter((x) => !member(x, s2), s1)
+
+  function intersection(s1 : set('a), s2 : set('a)) : set('a) =
+    filter((x) => member(x, s2), s1)
+
+  function intersection_list(sets : list(set('a))) : set('a) =
+    List.foldr(
+      intersection,
+      Option.default(new(), List.first(sets)),
+      Option.default([], List.tail(sets)))
+
+  function union(s1 : set('a), s2 : set('a)) : set('a) =
+    from_list(to_list(s1) ++ to_list(s2))
+
+  function union_list(sets : list(set('a))) : set('a) =
+    List.foldr(union, new(), sets)
@@ -15,7 +15,7 @@
            {base_plt_apps, [erts, kernel, stdlib, crypto, mnesia]}
           ]}.

-{relx, [{release, {aesophia, "6.0.2"},
+{relx, [{release, {aesophia, "6.1.0"},
         [aesophia, aebytecode, getopt]},

        {dev_mode, true},
@@ -254,8 +254,8 @@ decode_contract(_) -> [].
 decode_funcs(Fs) -> [ decode_func(F) || F <- Fs ].

 %% decode_func(#{name := init}) -> [];
-decode_func(#{name := Name, payable := Payable, arguments := As, returns := T}) ->
-    ["  ", payable(Payable), "entrypoint ", io_lib:format("~s", [Name]), " : ",
+decode_func(#{name := Name, stateful:= Stateful, payable := Payable, arguments := As, returns := T}) ->
+    ["  ", payable(Payable), stateful(Stateful), "entrypoint ", io_lib:format("~s", [Name]), " : ",
     decode_args(As), " => ", decode_type(T), $\n].

 decode_args(As) ->
@@ -336,6 +336,9 @@ decode_tvar(#{name := N}) -> io_lib:format("~s", [N]).
 payable(true)  -> "payable ";
 payable(false) -> "".

+stateful(true)  -> "stateful ";
+stateful(false) -> "".
+
 %% #contract{Ann, Con, [Declarations]}.

 contract_funcs({C, _, _, Decls}) when ?IS_CONTRACT_HEAD(C); C == namespace ->
@@ -102,6 +102,10 @@
 -type qname() :: [string()].
 -type typesig() :: {type_sig, aeso_syntax:ann(), type_constraints(), [aeso_syntax:named_arg_t()], [type()], type()}.

+-type namespace_alias() :: none | name().
+-type namespace_parts() :: none | {for, [name()]} | {hiding, [name()]}.
+-type used_namespaces() :: [{qname(), namespace_alias(), namespace_parts()}].
+
 -type type_constraints() :: none | bytes_concat | bytes_split | address_to_contract | bytecode_hash.

 -type fun_info()  :: {aeso_syntax:ann(), typesig() | type()}.
@@ -121,15 +125,17 @@
 -type scope() :: #scope{}.

 -record(env,
-    { scopes     = #{ [] => #scope{}} :: #{ qname() => scope() }
-    , vars       = []                 :: [{name(), var_info()}]
-    , typevars   = unrestricted       :: unrestricted | [name()]
-    , fields     = #{}                :: #{ name() => [field_info()] }    %% fields are global
-    , namespace  = []                 :: qname()
-    , in_pattern = false              :: boolean()
-    , stateful   = false              :: boolean()
-    , current_function = none         :: none | aeso_syntax:id()
-    , what       = top                :: top | namespace | contract | contract_interface
+    { scopes           = #{ [] => #scope{}} :: #{ qname() => scope() }
+    , vars             = []                 :: [{name(), var_info()}]
+    , typevars         = unrestricted       :: unrestricted | [name()]
+    , fields           = #{}                :: #{ name() => [field_info()] }    %% fields are global
+    , namespace        = []                 :: qname()
+    , used_namespaces  = []                 :: used_namespaces()
+    , in_pattern       = false              :: boolean()
+    , in_guard         = false              :: boolean()
+    , stateful         = false              :: boolean()
+    , current_function = none               :: none | aeso_syntax:id()
+    , what             = top                :: top | namespace | contract | contract_interface
    }).

 -type env() :: #env{}.
@@ -279,7 +285,7 @@ bind_contract({Contract, Ann, Id, Contents}, Env)
           contract_call_type(
             {fun_t, AnnF, [], [ArgT || {typed, _, _, ArgT} <- Args], RetT})
          }
-          || {letfun, AnnF, Entrypoint = {id, _, Name}, Args, _Type, {typed, _, _, RetT}} <- Contents,
+          || {letfun, AnnF, Entrypoint = {id, _, Name}, Args, _Type, [{guarded, _, [], {typed, _, _, RetT}}]} <- Contents,
             Name =/= "init"
        ] ++
        %% Predefined fields
@@ -312,9 +318,38 @@ bind_contract({Contract, Ann, Id, Contents}, Env)

 %% What scopes could a given name come from?
 -spec possible_scopes(env(), qname()) -> [qname()].
-possible_scopes(#env{ namespace = Current}, Name) ->
+possible_scopes(#env{ namespace = Current, used_namespaces = UsedNamespaces }, Name) ->
    Qual = lists:droplast(Name),
-    [ lists:sublist(Current, I) ++ Qual || I <- lists:seq(0, length(Current)) ].
+    NewQuals = case lists:filter(fun(X) -> element(2, X) == Qual end, UsedNamespaces) of
+                   [] ->
+                       [Qual];
+                   Namespaces ->
+                       lists:map(fun(X) -> element(1, X) end, Namespaces)
+               end,
+    Ret1 = [ lists:sublist(Current, I) ++ Q || I <- lists:seq(0, length(Current)), Q <- NewQuals ],
+    Ret2 = [ Namespace ++ Q || {Namespace, none, _} <- UsedNamespaces, Q <- NewQuals ],
+    lists:usort(Ret1 ++ Ret2).
+
+-spec visible_in_used_namespaces(used_namespaces(), qname()) -> boolean().
+visible_in_used_namespaces(UsedNamespaces, QName) ->
+    Qual = lists:droplast(QName),
+    Name = lists:last(QName),
+    case lists:filter(fun({Ns, _, _}) -> Qual == Ns end, UsedNamespaces) of
+        [] ->
+            true;
+        Namespaces ->
+            IsVisible = fun(Namespace) ->
+                            case Namespace of
+                                {_, _, {for, Names}} ->
+                                    lists:member(Name, Names);
+                                {_, _, {hiding, Names}} ->
+                                    not lists:member(Name, Names);
+                                _ ->
+                                    true
+                            end
+                        end,
+            lists:any(IsVisible, Namespaces)
+    end.

 -spec lookup_type(env(), type_id()) -> false | {qname(), type_info()}.
 lookup_type(Env, Id) ->
@@ -341,7 +376,7 @@ lookup_env(Env, Kind, Ann, Name) ->
    end.

 -spec lookup_env1(env(), type | term, aeso_syntax:ann(), qname()) -> false | {qname(), fun_info()}.
-lookup_env1(#env{ namespace = Current, scopes = Scopes }, Kind, Ann, QName) ->
+lookup_env1(#env{ namespace = Current, used_namespaces = UsedNamespaces, scopes = Scopes }, Kind, Ann, QName) ->
    Qual = lists:droplast(QName),
    Name = lists:last(QName),
    AllowPrivate = lists:prefix(Qual, Current),
@@ -365,7 +400,11 @@ lookup_env1(#env{ namespace = Current, scopes = Scopes }, Kind, Ann, QName) ->
                {Ann1, _} = E ->
                    %% Check that it's not private (or we can see private funs)
                    case not is_private(Ann1) orelse AllowPrivate of
-                        true  -> {QName, E};
+                        true  ->
+                            case visible_in_used_namespaces(UsedNamespaces, QName) of
+                                true -> {QName, E};
+                                false -> false
+                            end;
                        false -> false
                    end
            end
@@ -803,6 +842,8 @@ infer1(Env, [{namespace, Ann, Name, Code} | Rest], Acc, Options) ->
    {Env1, Code1} = infer_contract_top(push_scope(namespace, Name, Env), namespace, Code, Options),
    Namespace1 = {namespace, Ann, Name, Code1},
    infer1(pop_scope(Env1), Rest, [Namespace1 | Acc], Options);
+infer1(Env, [Using = {using, _, _, _, _} | Rest], Acc, Options) ->
+    infer1(check_usings(Env, Using), Rest, Acc, Options);
 infer1(Env, [{pragma, _, _} | Rest], Acc, Options) ->
    %% Pragmas are checked in check_modifiers
    infer1(Env, Rest, Acc, Options).
@@ -859,10 +900,13 @@ infer_contract(Env0, What, Defs0, Options) ->
              ({letfun, _, _, _, _, _})   -> function;
              ({fun_clauses, _, _, _, _}) -> function;
              ({fun_decl, _, _, _})       -> prototype;
+              ({using, _, _, _, _})       -> using;
              (_)                         -> unexpected
           end,
    Get = fun(K, In) -> [ Def || Def <- In, Kind(Def) == K ] end,
-    {Env1, TypeDefs} = check_typedefs(Env, Get(type, Defs)),
+    OldUsedNamespaces = Env#env.used_namespaces,
+    Env01 = check_usings(Env, Get(using, Defs)),
+    {Env1, TypeDefs} = check_typedefs(Env01, Get(type, Defs)),
    create_type_errors(),
    check_unexpected(Get(unexpected, Defs)),
    Env2 =
@@ -884,11 +928,13 @@ infer_contract(Env0, What, Defs0, Options) ->
    DepGraph  = maps:map(fun(_, Def) -> aeso_syntax_utils:used_ids(Def) end, FunMap),
    SCCs      = aeso_utils:scc(DepGraph),
    {Env4, Defs1} = check_sccs(Env3, FunMap, SCCs, []),
+    %% Remove namespaces used in the current namespace
+    Env5 = Env4#env{ used_namespaces = OldUsedNamespaces },
    %% Check that `init` doesn't read or write the state
    check_state_dependencies(Env4, Defs1),
    destroy_and_report_type_errors(Env4),
    %% Add inferred types of definitions
-    {Env4, TypeDefs ++ Decls ++ Defs1}.
+    {Env5, TypeDefs ++ Decls ++ Defs1}.

 %% Restructure blocks into multi-clause fundefs (`fun_clauses`).
 -spec process_blocks([aeso_syntax:decl()]) -> [aeso_syntax:decl()].
@@ -988,6 +1034,43 @@ check_typedef(Env, {variant_t, Cons}) ->
    {variant_t, [ {constr_t, Ann, Con, [ check_type(Env, Arg) || Arg <- Args ]}
                || {constr_t, Ann, Con, Args} <- Cons ]}.

+check_usings(Env, []) ->
+    Env;
+check_usings(Env = #env{ used_namespaces = UsedNamespaces }, [{using, Ann, Con, Alias, Parts} | Rest]) ->
+    AliasName = case Alias of
+                    none ->
+                        none;
+                    _ ->
+                        qname(Alias)
+                end,
+    case get_scope(Env, qname(Con)) of
+        false ->
+            create_type_errors(),
+            type_error({using_undefined_namespace, Ann, qname(Con)}),
+            destroy_and_report_type_errors(Env);
+        Scope ->
+            Nsp = case Parts of
+                      none ->
+                          {qname(Con), AliasName, none};
+                      {ForOrHiding, Ids} ->
+                          IsUndefined = fun(Id) ->
+                                            proplists:lookup(name(Id), Scope#scope.funs) == none
+                                        end,
+                          UndefinedIds = lists:filter(IsUndefined, Ids),
+                          case UndefinedIds of
+                              [] ->
+                                  {qname(Con), AliasName, {ForOrHiding, lists:map(fun name/1, Ids)}};
+                              _ ->
+                                  create_type_errors(),
+                                  type_error({using_undefined_namespace_parts, Ann, qname(Con), lists:map(fun qname/1, UndefinedIds)}),
+                                  destroy_and_report_type_errors(Env)
+                          end
+                  end,
+            check_usings(Env#env{ used_namespaces = UsedNamespaces ++ [Nsp] }, Rest)
+    end;
+check_usings(Env, Using = {using, _, _, _, _}) ->
+    check_usings(Env, [Using]).
+
 check_unexpected(Xs) ->
    [ type_error(X) || X <- Xs ].

@@ -1017,6 +1100,8 @@ check_modifiers_(Env, [{namespace, _, _, Decls} | Rest]) ->
 check_modifiers_(Env, [{pragma, Ann, Pragma} | Rest]) ->
    check_pragma(Env, Ann, Pragma),
    check_modifiers_(Env, Rest);
+check_modifiers_(Env, [{using, _, _, _, _} | Rest]) ->
+    check_modifiers_(Env, Rest);
 check_modifiers_(Env, [Decl | Rest]) ->
    type_error({bad_top_level_decl, Decl}),
    check_modifiers_(Env, Rest);
@@ -1272,23 +1357,29 @@ infer_letfun(Env, {fun_clauses, Ann, Fun = {id, _, Name}, Type, Clauses}) ->
 infer_letfun(Env, LetFun = {letfun, Ann, Fun, _, _, _}) ->
    {{Name, Sig}, Clause} = infer_letfun1(Env, LetFun),
    {{Name, Sig}, desugar_clauses(Ann, Fun, Sig, [Clause])}.
-
-infer_letfun1(Env0, {letfun, Attrib, Fun = {id, NameAttrib, Name}, Args, What, Body}) ->
+infer_letfun1(Env0, {letfun, Attrib, Fun = {id, NameAttrib, Name}, Args, What, GuardedBodies}) ->
    Env = Env0#env{ stateful = aeso_syntax:get_ann(stateful, Attrib, false),
                    current_function = Fun },
    {NewEnv, {typed, _, {tuple, _, TypedArgs}, {tuple_t, _, ArgTypes}}} = infer_pattern(Env, {tuple, [{origin, system} | NameAttrib], Args}),
    ExpectedType = check_type(Env, arg_type(NameAttrib, What)),
-    NewBody={typed, _, _, ResultType} = check_expr(NewEnv, Body, ExpectedType),
+    InferGuardedBodies = fun({guarded, Ann, Guards, Body}) ->
+        NewGuards = lists:map(fun(Guard) ->
+                                  check_expr(NewEnv#env{ in_guard = true }, Guard, {id, Attrib, "bool"})
+                              end, Guards),
+        NewBody = check_expr(NewEnv, Body, ExpectedType),
+        {guarded, Ann, NewGuards, NewBody}
+    end,
+    NewGuardedBodies = [{guarded, _, _, {typed, _, _, ResultType}} | _] = lists:map(InferGuardedBodies, GuardedBodies),
    NamedArgs = [],
    TypeSig = {type_sig, Attrib, none, NamedArgs, ArgTypes, ResultType},
    {{Name, TypeSig},
-     {letfun, Attrib, {id, NameAttrib, Name}, TypedArgs, ResultType, NewBody}}.
+     {letfun, Attrib, {id, NameAttrib, Name}, TypedArgs, ResultType, NewGuardedBodies}}.

 desugar_clauses(Ann, Fun, {type_sig, _, _, _, ArgTypes, RetType}, Clauses) ->
    NeedDesugar =
        case Clauses of
-            [{letfun, _, _, As, _, _}] -> lists:any(fun({typed, _, {id, _, _}, _}) -> false; (_) -> true end, As);
-            _                          -> true
+            [{letfun, _, _, As, _, [{guarded, _, [], _}]}] -> lists:any(fun({typed, _, {id, _, _}, _}) -> false; (_) -> true end, As);
+            _                                              -> true
        end,
    case NeedDesugar of
        false -> [Clause] = Clauses, Clause;
@@ -1299,11 +1390,10 @@ desugar_clauses(Ann, Fun, {type_sig, _, _, _, ArgTypes, RetType}, Clauses) ->
            Tuple = fun([X]) -> X;
                       (As) -> {typed, NoAnn, {tuple, NoAnn, As}, {tuple_t, NoAnn, ArgTypes}}
                    end,
-            {letfun, Ann, Fun, Args, RetType,
-             {typed, NoAnn,
-              {switch, NoAnn, Tuple(Args),
-                [ {'case', AnnC, Tuple(ArgsC), Body}
-                || {letfun, AnnC, _, ArgsC, _, Body} <- Clauses ]}, RetType}}
+            {letfun, Ann, Fun, Args, RetType, [{guarded, NoAnn, [], {typed, NoAnn,
+               {switch, NoAnn, Tuple(Args),
+                 [ {'case', AnnC, Tuple(ArgsC), GuardedBodies}
+                 || {letfun, AnnC, _, ArgsC, _, GuardedBodies} <- Clauses ]}, RetType}}]}
    end.

 print_typesig({Name, TypeSig}) ->
@@ -1341,6 +1431,12 @@ lookup_name(Env, As, Id, Options) ->
            {set_qname(QId, Id), Ty1}
    end.

+check_stateful(#env{ in_guard = true }, Id, Type = {type_sig, _, _, _, _, _}) ->
+    case aeso_syntax:get_ann(stateful, Type, false) of
+        false -> ok;
+        true  ->
+            type_error({stateful_not_allowed_in_guards, Id})
+    end;
 check_stateful(#env{ stateful = false, current_function = Fun }, Id, Type = {type_sig, _, _, _, _, _}) ->
    case aeso_syntax:get_ann(stateful, Type, false) of
        false -> ok;
@@ -1365,7 +1461,7 @@ check_state_dependencies(Env, Defs) ->
    SetState  = Top ++ ["put"],
    Init      = Top ++ ["init"],
    UsedNames = fun(X) -> [{Xs, Ann} || {{term, Xs}, Ann} <- aeso_syntax_utils:used(X)] end,
-    Funs      = [ {Top ++ [Name], Fun} || Fun = {letfun, _, {id, _, Name}, _Args, _Type, _Body} <- Defs ],
+    Funs      = [ {Top ++ [Name], Fun} || Fun = {letfun, _, {id, _, Name}, _Args, _Type, _GuardedBodies} <- Defs ],
    Deps      = maps:from_list([{Name, UsedNames(Def)} || {Name, Def} <- Funs]),
    case maps:get(Init, Deps, false) of
        false -> ok;    %% No init, so nothing to check
@@ -1469,12 +1565,12 @@ infer_expr(Env, {list_comp, AttrsL, Yield, [{comprehension_if, AttrsIF, Cond}|Re
 infer_expr(Env, {list_comp, AsLC, Yield, [{letval, AsLV, Pattern, E}|Rest]}) ->
    NewE = {typed, _, _, PatType} = infer_expr(Env, E),
    BlockType = fresh_uvar(AsLV),
-    {'case', _, NewPattern, NewRest} =
+    {'case', _, NewPattern, [{guarded, _, [], NewRest}]} =
        infer_case( Env
                  , AsLC
                  , Pattern
                  , PatType
-                  , {list_comp, AsLC, Yield, Rest}
+                  , [{guarded, AsLC, [], {list_comp, AsLC, Yield, Rest}}]
                  , BlockType),
    {typed, _, {list_comp, _, TypedYield, TypedRest}, ResType} = NewRest,
    { typed
@@ -1532,8 +1628,8 @@ infer_expr(Env, {'if', Attrs, Cond, Then, Else}) ->
 infer_expr(Env, {switch, Attrs, Expr, Cases}) ->
    NewExpr = {typed, _, _, ExprType} = infer_expr(Env, Expr),
    SwitchType = fresh_uvar(Attrs),
-    NewCases = [infer_case(Env, As, Pattern, ExprType, Branch, SwitchType)
-                || {'case', As, Pattern, Branch} <- Cases],
+    NewCases = [infer_case(Env, As, Pattern, ExprType, GuardedBranches, SwitchType)
+                || {'case', As, Pattern, GuardedBranches} <- Cases],
    {typed, Attrs, {switch, Attrs, NewExpr, NewCases}, SwitchType};
 infer_expr(Env, {record, Attrs, Fields}) ->
    RecordType = fresh_uvar(Attrs),
@@ -1615,10 +1711,13 @@ infer_expr(Env, {lam, Attrs, Args, Body}) ->
    ArgTypes = [fresh_uvar(As) || {arg, As, _, _} <- Args],
    ArgPatterns = [{typed, As, Pat, check_type(Env, T)} || {arg, As, Pat, T} <- Args],
    ResultType = fresh_uvar(Attrs),
-    {'case', _, {typed, _, {tuple, _, NewArgPatterns}, _}, NewBody} =
-        infer_case(Env, Attrs, {tuple, Attrs, ArgPatterns}, {tuple_t, Attrs, ArgTypes}, Body, ResultType),
+    {'case', _, {typed, _, {tuple, _, NewArgPatterns}, _}, [{guarded, _, [], NewBody}]} =
+        infer_case(Env, Attrs, {tuple, Attrs, ArgPatterns}, {tuple_t, Attrs, ArgTypes}, [{guarded, Attrs, [], Body}], ResultType),
    NewArgs = [{arg, As, NewPat, NewT} || {typed, As, NewPat, NewT} <- NewArgPatterns],
    {typed, Attrs, {lam, Attrs, NewArgs, NewBody}, {fun_t, Attrs, [], ArgTypes, ResultType}};
+infer_expr(Env, {letpat, Attrs, Id, Pattern}) ->
+    NewPattern = {typed, _, _, PatType} = infer_expr(Env, Pattern),
+    {typed, Attrs, {letpat, Attrs, check_expr(Env, Id, PatType), NewPattern}, PatType};
 infer_expr(Env, Let = {letval, Attrs, _, _}) ->
    type_error({missing_body_for_let, Attrs}),
    infer_expr(Env, {block, Attrs, [Let, abort_expr(Attrs, "missing body")]});
@@ -1749,11 +1848,18 @@ infer_pattern(Env, Pattern) ->
    NewPattern = infer_expr(NewEnv, Pattern),
    {NewEnv#env{ in_pattern = Env#env.in_pattern }, NewPattern}.

-infer_case(Env, Attrs, Pattern, ExprType, Branch, SwitchType) ->
+infer_case(Env, Attrs, Pattern, ExprType, GuardedBranches, SwitchType) ->
    {NewEnv, NewPattern = {typed, _, _, PatType}} = infer_pattern(Env, Pattern),
-    NewBranch  = check_expr(NewEnv#env{ in_pattern = false }, Branch, SwitchType),
+    InferGuardedBranches = fun({guarded, Ann, Guards, Branch}) ->
+        NewGuards = lists:map(fun(Guard) ->
+                                  check_expr(NewEnv#env{ in_guard = true }, Guard, {id, Attrs, "bool"})
+                              end, Guards),
+        NewBranch = check_expr(NewEnv#env{ in_pattern = false }, Branch, SwitchType),
+        {guarded, Ann, NewGuards, NewBranch}
+    end,
+    NewGuardedBranches = lists:map(InferGuardedBranches, GuardedBranches),
    unify(Env, PatType, ExprType, {case_pat, Pattern, PatType, ExprType}),
-    {'case', Attrs, NewPattern, NewBranch}.
+    {'case', Attrs, NewPattern, NewGuardedBranches}.

 %% NewStmts = infer_block(Env, Attrs, Stmts, BlockType)
 infer_block(_Env, Attrs, [], BlockType) ->
@@ -1767,9 +1873,11 @@ infer_block(Env, Attrs, [Def={letfun, Ann, _, _, _, _}|Rest], BlockType) ->
    [LetFun|infer_block(NewE, Attrs, Rest, BlockType)];
 infer_block(Env, _, [{letval, Attrs, Pattern, E}|Rest], BlockType) ->
    NewE = {typed, _, _, PatType} = infer_expr(Env, E),
-    {'case', _, NewPattern, {typed, _, {block, _, NewRest}, _}} =
-        infer_case(Env, Attrs, Pattern, PatType, {block, Attrs, Rest}, BlockType),
+    {'case', _, NewPattern, [{guarded, _, [], {typed, _, {block, _, NewRest}, _}}]} =
+        infer_case(Env, Attrs, Pattern, PatType, [{guarded, Attrs, [], {block, Attrs, Rest}}], BlockType),
    [{letval, Attrs, NewPattern, NewE}|NewRest];
+infer_block(Env, Attrs, [Using = {using, _, _, _, _} | Rest], BlockType) ->
+    infer_block(check_usings(Env, Using), Attrs, Rest, BlockType);
 infer_block(Env, Attrs, [E|Rest], BlockType) ->
    [infer_expr(Env, E)|infer_block(Env, Attrs, Rest, BlockType)].

@@ -1832,6 +1940,8 @@ free_vars({record, _, Fields}) ->
    free_vars([E || {field, _, _, E} <- Fields]);
 free_vars({typed, _, A, _}) ->
    free_vars(A);
+free_vars({letpat, _, Id, Pat}) ->
+    free_vars(Id) ++ free_vars(Pat);
 free_vars(L) when is_list(L) ->
    [V || Elem <- L,
          V <- free_vars(Elem)].
@@ -2333,8 +2443,8 @@ unfold_types(Env, {type_def, Ann, Name, Args, Def}, Options) ->
    {type_def, Ann, Name, Args, unfold_types_in_type(Env, Def, Options)};
 unfold_types(Env, {fun_decl, Ann, Name, Type}, Options) ->
    {fun_decl, Ann, Name, unfold_types(Env, Type, Options)};
-unfold_types(Env, {letfun, Ann, Name, Args, Type, Body}, Options) ->
-    {letfun, Ann, Name, unfold_types(Env, Args, Options), unfold_types_in_type(Env, Type, Options), unfold_types(Env, Body, Options)};
+unfold_types(Env, {letfun, Ann, Name, Args, Type, [{guarded, AnnG, [], Body}]}, Options) ->
+    {letfun, Ann, Name, unfold_types(Env, Args, Options), unfold_types_in_type(Env, Type, Options), [{guarded, AnnG, [], unfold_types(Env, Body, Options)}]};
 unfold_types(Env, T, Options) when is_tuple(T) ->
    list_to_tuple(unfold_types(Env, tuple_to_list(T), Options));
 unfold_types(Env, [H|T], Options) ->
@@ -2835,6 +2945,10 @@ mk_error({stateful_not_allowed, Id, Fun}) ->
    Msg = io_lib:format("Cannot reference stateful function ~s (at ~s)\nin the definition of non-stateful function ~s.\n",
                        [pp(Id), pp_loc(Id), pp(Fun)]),
    mk_t_err(pos(Id), Msg);
+mk_error({stateful_not_allowed_in_guards, Id}) ->
+    Msg = io_lib:format("Cannot reference stateful function ~s (at ~s) in a pattern guard.\n",
+                        [pp(Id), pp_loc(Id)]),
+    mk_t_err(pos(Id), Msg);
 mk_error({value_arg_not_allowed, Value, Fun}) ->
    Msg = io_lib:format("Cannot pass non-zero value argument ~s (at ~s)\nin the definition of non-stateful function ~s.\n",
                        [pp_expr("", Value), pp_loc(Value), pp(Fun)]),
@@ -2987,6 +3101,17 @@ mk_error({contract_lacks_definition, Type, When}) ->
           ),
    {Pos, Ctxt} = pp_when(When),
    mk_t_err(Pos, Msg, Ctxt);
+mk_error({ambiguous_name, QIds = [{qid, Ann, _} | _]}) ->
+    Names = lists:map(fun(QId) -> io_lib:format("~s at ~s\n", [pp(QId), pp_loc(QId)]) end, QIds),
+    Msg = "Ambiguous name: " ++ lists:concat(Names),
+    mk_t_err(pos(Ann), Msg);
+mk_error({using_undefined_namespace, Ann, Namespace}) ->
+    Msg = io_lib:format("Cannot use undefined namespace ~s", [Namespace]),
+    mk_t_err(pos(Ann), Msg);
+mk_error({using_undefined_namespace_parts, Ann, Namespace, Parts}) ->
+    PartsStr = lists:concat(lists:join(", ", Parts)),
+    Msg = io_lib:format("The namespace ~s does not define the following names: ~s", [Namespace, PartsStr]),
+    mk_t_err(pos(Ann), Msg);
 mk_error(Err) ->
    Msg = io_lib:format("Unknown error: ~p\n", [Err]),
    mk_t_err(pos(0, 0), Msg).
@@ -96,7 +96,8 @@
                     | nil
                     | {'::', var_name(), var_name()}
                     | {con, arities(), tag(), [var_name()]}
-                     | {tuple, [var_name()]}.
+                     | {tuple, [var_name()]}
+                     | {assign, var_name(), var_name()}.

 -type ftype() :: integer
               | boolean
@@ -286,7 +287,7 @@ state_layout(Env) -> maps:get(state_layout, Env, {reg, 1}).
 -spec init_type_env() -> type_env().
 init_type_env() ->
    BaseTx = {variant, [[address, integer, string], [], [], [], [], [], [string],
-                        [hash], [hash], [address, hash], [address],
+                        [{bytes, 32}], [{bytes, 32}], [address, {bytes, 32}], [address],
                        [address, integer], [address, integer], [address],
                        [address], [address], [address], [address], [address],
                        [integer], [address, integer], []]},
@@ -384,7 +385,7 @@ decl_to_fcode(Env = #{context := {contract_def, _}}, {fun_decl, _, Id, _}) ->
 decl_to_fcode(Env, {fun_decl, _, _, _})  -> Env;
 decl_to_fcode(Env, {type_def, _Ann, Name, Args, Def}) ->
    typedef_to_fcode(Env, Name, Args, Def);
-decl_to_fcode(Env = #{ functions := Funs }, {letfun, Ann, Id = {id, _, Name}, Args, Ret, Body}) ->
+decl_to_fcode(Env = #{ functions := Funs }, {letfun, Ann, Id = {id, _, Name}, Args, Ret, [{guarded, _, [], Body}]}) ->
    Attrs = get_attributes(Ann),
    FName = lookup_fun(Env, qname(Env, Name)),
    FArgs = args_to_fcode(Env, Args),
@@ -661,8 +662,8 @@ expr_to_fcode(Env, _Type, {list_comp, As, Yield, [{comprehension_bind, Pat = {ty
    Arg  = fresh_name(),
    Env1 = bind_var(Env, Arg),
    Bind = {lam, [Arg], expr_to_fcode(Env1, {switch, As, {typed, As, {id, As, Arg}, PatType},
-                                                [{'case', As, Pat, {list_comp, As, Yield, Rest}},
-                                                 {'case', As, {id, As, "_"}, {list, As, []}}]})},
+                                                [{'case', As, Pat, [{guarded, As, [], {list_comp, As, Yield, Rest}}]},
+                                                 {'case', As, {id, As, "_"}, [{guarded, As, [], {list, As, []}}]}]})},
    {def_u, FlatMap, _} = resolve_fun(Env, ["ListInternal", "flat_map"]),
    {def, FlatMap, [Bind, expr_to_fcode(Env, BindExpr)]};
 expr_to_fcode(Env, Type, {list_comp, As, Yield, [{comprehension_if, _, Cond}|Rest]}) ->
@@ -682,9 +683,9 @@ expr_to_fcode(Env, _Type, {'if', _, Cond, Then, Else}) ->
            expr_to_fcode(Env, Else));

 %% Switch
-expr_to_fcode(Env, _, {switch, _, Expr = {typed, _, E, Type}, Alts}) ->
+expr_to_fcode(Env, _, S = {switch, _, Expr = {typed, _, E, Type}, Alts}) ->
    Switch = fun(X) ->
-                {switch, alts_to_fcode(Env, type_to_fcode(Env, Type), X, Alts)}
+                {switch, alts_to_fcode(Env, type_to_fcode(Env, Type), X, Alts, S)}
             end,
    case E of
        {id, _, X} -> Switch(X);
@@ -797,6 +798,13 @@ make_if(Cond, Then, Else) ->
    X = fresh_name(),
    {'let', X, Cond, make_if({var, X}, Then, Else)}.

+make_if_no_else({var, X}, Then) ->
+    {switch, {split, boolean, X,
+        [{'case', {bool, true},  {nosplit, Then}}]}};
+make_if_no_else(Cond, Then) ->
+    X = fresh_name(),
+    {'let', X, Cond, make_if_no_else({var, X}, Then)}.
+
 -spec make_tuple([fexpr()]) -> fexpr().
 make_tuple([E]) -> E;
 make_tuple(Es) -> {tuple, Es}.
@@ -862,9 +870,9 @@ is_first_order(_)                      -> true.

 %% -- Pattern matching --

-spec alts_to_fcode(env(), ftype(), var_name(), [aeso_syntax:alt()]) -> fsplit().
-alts_to_fcode(Env, Type, X, Alts) ->
-    FAlts = [alt_to_fcode(Env, Alt) || Alt <- Alts],
+-spec alts_to_fcode(env(), ftype(), var_name(), [aeso_syntax:alt()], aeso_syntax:expr()) -> fsplit().
+alts_to_fcode(Env, Type, X, Alts, Switch) ->
+    FAlts = remove_guards(Env, Alts, Switch),
    split_tree(Env, [{X, Type}], FAlts).

 %% Intermediate format before case trees (fcase() and fsplit()).
@@ -875,7 +883,43 @@ alts_to_fcode(Env, Type, X, Alts) ->
              | {string, binary()}
              | nil | {'::', fpat(), fpat()}
              | {tuple, [fpat()]}
-              | {con, arities(), tag(), [fpat()]}.
+              | {con, arities(), tag(), [fpat()]}
+              | {assign, fpat(), fpat()}.
+
+remove_guards(_Env, [], _Switch) ->
+    [];
+remove_guards(Env, [Alt = {'case', _, _, [{guarded, _, [], _Expr}]} | Rest], Switch) ->
+    [alt_to_fcode(Env, Alt) | remove_guards(Env, Rest, Switch)];
+remove_guards(Env, [{'case', AnnC, Pat, [{guarded, AnnG, [Guard | Guards], Body} | GuardedBodies]} | Rest], Switch = {switch, Ann, Expr, _}) ->
+    FPat = pat_to_fcode(Env, Pat),
+    FGuard = expr_to_fcode(bind_vars(Env, pat_vars(FPat)), Guard),
+    FBody = expr_to_fcode(bind_vars(Env, pat_vars(FPat)), Body),
+    case Guards of
+        [] ->
+            R = case GuardedBodies of
+                    [] -> Rest;
+                    _  -> [{'case', AnnC, Pat, GuardedBodies} | Rest]
+                end,
+            case R of
+                [] ->
+                    [{'case', [FPat], make_if_no_else(FGuard, FBody)} | remove_guards(Env, Rest, Switch)];
+                _ ->
+                    FSwitch = expr_to_fcode(Env, {switch, Ann, Expr, R}),
+                    [{'case', [FPat], make_if(FGuard, FBody, FSwitch)} | remove_guards(Env, Rest, Switch)]
+            end;
+        _ ->
+            R1 = case GuardedBodies of
+                     [] -> [{'case', AnnC, Pat, [{guarded, AnnG, Guards, Body}]} | Rest];
+                     _  -> [{'case', AnnC, Pat, [{guarded, AnnG, Guards, Body} | GuardedBodies]} | Rest]
+                 end,
+            R2 = case GuardedBodies of
+                     [] -> Rest;
+                     _  -> [{'case', AnnC, Pat, GuardedBodies} | Rest]
+                 end,
+            FSwitch1 = expr_to_fcode(Env, {switch, Ann, Expr, R1}),
+            FSwitch2 = expr_to_fcode(Env, {switch, Ann, Expr, R2}),
+            [{'case', [FPat], make_if(FGuard, FSwitch1, FSwitch2)} | remove_guards(Env, Rest, Switch)]
+    end.

 %% %% Invariant: the number of variables matches the number of patterns in each falt.
 -spec split_tree(env(), [{var_name(), ftype()}], [falt()]) -> fsplit().
@@ -975,6 +1019,8 @@ split_pat({'::', P, Q}) -> {{'::', fresh_name(), fresh_name()}, [P, Q]};
 split_pat({con, As, I, Pats}) ->
    Xs = [fresh_name() || _ <- Pats],
    {{con, As, I, Xs}, Pats};
+split_pat({assign, X = {var, _}, P}) ->
+    {{assign, fresh_name(), fresh_name()}, [X, P]};
 split_pat({tuple, Pats}) ->
    Xs = [fresh_name() || _ <- Pats],
    {{tuple, Xs}, Pats}.
@@ -985,6 +1031,7 @@ split_vars({int, _},    integer)     -> [];
 split_vars({string, _}, string)      -> [];
 split_vars(nil,         {list, _})   -> [];
 split_vars({'::', X, Xs}, {list, T}) -> [{X, T}, {Xs, {list, T}}];
+split_vars({assign, X, P}, T)        -> [{X, T}, {P, T}];
 split_vars({con, _, I, Xs}, {variant, Cons}) ->
    lists:zip(Xs, lists:nth(I + 1, Cons));
 split_vars({tuple, Xs}, {tuple, Ts}) ->
@@ -1000,7 +1047,7 @@ next_split(Pats) ->
    end.

 -spec alt_to_fcode(env(), aeso_syntax:alt()) -> falt().
-alt_to_fcode(Env, {'case', _, Pat, Expr}) ->
+alt_to_fcode(Env, {'case', _, Pat, [{guarded, _, [], Expr}]}) ->
    FPat  = pat_to_fcode(Env, Pat),
    FExpr = expr_to_fcode(bind_vars(Env, pat_vars(FPat)), Expr),
    {'case', [FPat], FExpr}.
@@ -1040,6 +1087,8 @@ pat_to_fcode(Env, {record_t, Fields}, {record, _, FieldPats}) ->
                    end end,
    make_tuple([pat_to_fcode(Env, FieldPat(Field))
                || Field <- Fields]);
+pat_to_fcode(Env, _Type, {letpat, _, Id = {typed, _, {id, _, _}, _}, Pattern}) ->
+    {assign, pat_to_fcode(Env, Id), pat_to_fcode(Env, Pattern)};

 pat_to_fcode(_Env, Type, Pat) ->
    error({todo, Pat, ':', Type}).
@@ -1076,8 +1125,8 @@ decision_tree_to_fcode({'if', A, Then, Else}) ->
 stmts_to_fcode(Env, [{letval, _, {typed, _, {id, _, X}, _}, Expr} | Stmts]) ->
    {'let', X, expr_to_fcode(Env, Expr), stmts_to_fcode(bind_var(Env, X), Stmts)};
 stmts_to_fcode(Env, [{letval, Ann, Pat, Expr} | Stmts]) ->
-    expr_to_fcode(Env, {switch, Ann, Expr, [{'case', Ann, Pat, {block, Ann, Stmts}}]});
-stmts_to_fcode(Env, [{letfun, Ann, {id, _, X}, Args, _Type, Expr} | Stmts]) ->
+    expr_to_fcode(Env, {switch, Ann, Expr, [{'case', Ann, Pat, [{guarded, Ann, [], {block, Ann, Stmts}}]}]});
+stmts_to_fcode(Env, [{letfun, Ann, {id, _, X}, Args, _Type, [{guarded, _, [], Expr}]} | Stmts]) ->
    LamArgs = [ case Arg of
                    {typed, Ann1, Id, T} -> {arg, Ann1, Id, T};
                    _ -> internal_error({bad_arg, Arg})   %% pattern matching has been desugared
@@ -1530,6 +1579,7 @@ match_pat(L, {lit, L})                      -> [];
 match_pat(nil, nil)                         -> [];
 match_pat({'::', X, Y}, {op, '::', [A, B]}) -> [{X, A}, {Y, B}];
 match_pat({var, X}, E)                      -> [{X, E}];
+match_pat({assign, X, P}, E)                -> [{X, E}, {P, E}];
 match_pat(_, _)                             -> false.

 constructor_form(Env, Expr) ->
@@ -1765,6 +1815,7 @@ pat_vars(nil)                 -> [];
 pat_vars({'::', P, Q})        -> pat_vars(P) ++ pat_vars(Q);
 pat_vars({tuple, Ps})         -> pat_vars(Ps);
 pat_vars({con, _, _, Ps})     -> pat_vars(Ps);
+pat_vars({assign, X, P})      -> pat_vars(X) ++ pat_vars(P);
 pat_vars(Ps) when is_list(Ps) -> [X || P <- Ps, X <- pat_vars(P)].

 -spec fsplit_pat_vars(fsplit_pat()) -> [var_name()].
@@ -1985,7 +2036,11 @@ rename_spat(Ren, {con, Ar, C, Xs}) ->
    {{con, Ar, C, Zs}, Ren1};
 rename_spat(Ren, {tuple, Xs}) ->
    {Zs, Ren1} = rename_bindings(Ren, Xs),
-    {{tuple, Zs}, Ren1}.
+    {{tuple, Zs}, Ren1};
+rename_spat(Ren, {assign, X, P}) ->
+    {X1, Ren1} = rename_binding(Ren, X),
+    {P1, Ren2} = rename_binding(Ren1, P),
+    {{assign, X1, P1}, Ren2}.

 rename_split(Ren, {split, Type, X, Cases}) ->
    {split, Type, rename_var(Ren, X), [rename_case(Ren, C) || C <- Cases]};
@@ -96,7 +96,7 @@ contract_to_icode([Decl = {type_def, _Attrib, Id = {id, _, Name}, Args, Def} | R
                _                       -> Icode1
             end,
    contract_to_icode(Rest, Icode2);
-contract_to_icode([{letfun, Attrib, Name, Args, _What, Body={typed,_,_,T}}|Rest], Icode) ->
+contract_to_icode([{letfun, Attrib, Name, Args, _What, [{guarded, _, [], Body={typed,_,_,T}}]}|Rest], Icode) ->
    FunAttrs = [ stateful || proplists:get_value(stateful, Attrib, false) ] ++
               [ payable  || proplists:get_value(payable, Attrib, false) ] ++
               [ private  || is_private(Attrib, Icode) ],
@@ -323,8 +323,8 @@ ast_body({list_comp, _, Yield, []}, Icode) ->
 ast_body({list_comp, As, Yield, [{comprehension_bind, {typed, _, Pat, ArgType}, BindExpr}|Rest]}, Icode) ->
    Arg  = "%lc",
    Body = {switch, As, {typed, As, {id, As, Arg}, ArgType},
-                [{'case', As, Pat, {list_comp, As, Yield, Rest}},
-                 {'case', As, {id, As, "_"}, {list, As, []}}]},
+                [{'case', As, Pat, [{guarded, As, [], {list_comp, As, Yield, Rest}}]},
+                 {'case', As, {id, As, "_"}, [{guarded, As, [], {list, As, []}}]}]},
    #funcall
        { function = #var_ref{ name = ["ListInternal", "flat_map"] }
        , args =
@@ -349,14 +349,14 @@ ast_body({switch,_,A,Cases}, Icode) ->
    %% patterns appear in cases.
    #switch{expr=ast_body(A, Icode),
            cases=[{ast_body(Pat, Icode),ast_body(Body, Icode)}
-              || {'case',_,Pat,Body} <- Cases]};
+              || {'case',_,Pat,[{guarded, _, [], Body}]} <- Cases]};
 ast_body({block, As, [{letval, _, Pat, E} | Rest]}, Icode) ->
    E1    = ast_body(E, Icode),
    Pat1  = ast_body(Pat, Icode),
    Rest1 = ast_body({block, As, Rest}, Icode),
    #switch{expr  = E1,
            cases = [{Pat1, Rest1}]};
-ast_body({block, As, [{letfun, Ann, F, Args, _Type, Expr} | Rest]}, Icode) ->
+ast_body({block, As, [{letfun, Ann, F, Args, _Type, [{guarded, _, [], Expr}]} | Rest]}, Icode) ->
    ToArg   = fun({typed, Ann1, Id, T}) -> {arg, Ann1, Id, T} end,    %% Pattern matching has been desugared
    LamArgs = lists:map(ToArg, Args),
    ast_body({block, As, [{letval, Ann, F, {lam, Ann, LamArgs, Expr}} | Rest]}, Icode);
@@ -475,9 +475,9 @@ error_missing_call_function() ->
 get_call_type([{Contract, _, _, Defs}]) when ?IS_CONTRACT_HEAD(Contract) ->
    case [ {lists:last(QFunName), FunType}
          || {letfun, _, {id, _, ?CALL_NAME}, [], _Ret,
-                {typed, _,
-                    {app, _,
-                        {typed, _, {qid, _, QFunName}, FunType}, _}, _}} <- Defs ] of
+                [{guarded, _, [], {typed, _,
+                     {app, _,
+                         {typed, _, {qid, _, QFunName}, FunType}, _}, _}}]} <- Defs ] of
        [Call] -> {ok, Call};
        []     -> error_missing_call_function()
    end;
@@ -9,12 +9,14 @@
        false -> fail()
    end).

-define(RULE(A,                Do), map(fun(_1) ->                       Do end, A                 )).
-define(RULE(A, B,             Do), map(fun({_1, _2}) ->                 Do end, {A, B}            )).
-define(RULE(A, B, C,          Do), map(fun({_1, _2, _3}) ->             Do end, {A, B, C}         )).
-define(RULE(A, B, C, D,       Do), map(fun({_1, _2, _3, _4}) ->         Do end, {A, B, C, D}      )).
-define(RULE(A, B, C, D, E,    Do), map(fun({_1, _2, _3, _4, _5}) ->     Do end, {A, B, C, D, E}   )).
-define(RULE(A, B, C, D, E, F, Do), map(fun({_1, _2, _3, _4, _5, _6}) -> Do end, {A, B, C, D, E, F})).
+-define(RULE(A,                      Do), map(fun(_1) ->                               Do end, A                       )).
+-define(RULE(A, B,                   Do), map(fun({_1, _2}) ->                         Do end, {A, B}                  )).
+-define(RULE(A, B, C,                Do), map(fun({_1, _2, _3}) ->                     Do end, {A, B, C}               )).
+-define(RULE(A, B, C, D,             Do), map(fun({_1, _2, _3, _4}) ->                 Do end, {A, B, C, D}            )).
+-define(RULE(A, B, C, D, E,          Do), map(fun({_1, _2, _3, _4, _5}) ->             Do end, {A, B, C, D, E}         )).
+-define(RULE(A, B, C, D, E, F,       Do), map(fun({_1, _2, _3, _4, _5, _6}) ->         Do end, {A, B, C, D, E, F}      )).
+-define(RULE(A, B, C, D, E, F, G,    Do), map(fun({_1, _2, _3, _4, _5, _6, _7}) ->     Do end, {A, B, C, D, E, F, G}   )).
+-define(RULE(A, B, C, D, E, F, G, H, Do), map(fun({_1, _2, _3, _4, _5, _6, _7, _8}) -> Do end, {A, B, C, D, E, F, G, H})).

 -import(aeso_parse_lib,
        [tok/1, tok/2, between/3, many/1, many1/1, sep/2, sep1/2,
@@ -109,6 +109,7 @@ decl() ->

    , ?RULE(keyword(namespace), con(), tok('='), maybe_block(decl()), {namespace, _1, _2, _4})
    , ?RULE(keyword(include),   str(), {include, get_ann(_1), _2})
+    , using()
    , pragma()

      %% Type declarations  TODO: format annotation for "type bla" vs "type bla()"
@@ -135,6 +136,21 @@ fundef_or_decl() ->
    choice([?RULE(id(), tok(':'), type(), {fun_decl, get_ann(_1), _1, _3}),
            fundef()]).

+using() ->
+    Alias = {keyword(as), con()},
+    For = ?RULE(keyword(for), bracket_list(id()), {for, _2}),
+    Hiding = ?RULE(keyword(hiding), bracket_list(id()), {hiding, _2}),
+    ?RULE(keyword(using), con(), optional(Alias), optional(choice(For, Hiding)), using(get_ann(_1), _2, _3, _4)).
+
+using(Ann, Con, none, none) ->
+    {using, Ann, Con, none, none};
+using(Ann, Con, {ok, {_, Alias}}, none) ->
+    {using, Ann, Con, Alias, none};
+using(Ann, Con, none, {ok, List}) ->
+    {using, Ann, Con, none, List};
+using(Ann, Con, {ok, {_, Alias}}, {ok, List}) ->
+    {using, Ann, Con, Alias, List}.
+
 pragma() ->
    Op = choice([token(T) || T <- ['<', '=<', '==', '>=', '>']]),
    ?RULE(tok('@'), id("compiler"), Op, version(), {pragma, get_ann(_1), {compiler, element(1, _3), _4}}).
@@ -195,10 +211,16 @@ letdef() -> choice(valdef(), fundef()).
 valdef() ->
    ?RULE(pattern(), tok('='), body(), {letval, [], _1, _3}).

+guarded_fundefs() ->
+    choice(
+    [ ?RULE(keyword('='), body(), [{guarded, _1, [], _2}])
+    , maybe_block(?RULE(keyword('|'), comma_sep(expr()), tok('='), body(), {guarded, _1, _2, _4}))
+    ]).
+
 fundef() ->
    choice(
-    [ ?RULE(id(), args(),                   tok('='), body(), {letfun, get_ann(_1), _1, _2, type_wildcard(get_ann(_1)), _4})
-    , ?RULE(id(), args(), tok(':'), type(), tok('='), body(), {letfun, get_ann(_1), _1, _2, _4, _6})
+    [ ?RULE(id(), args(),                   guarded_fundefs(), {letfun, get_ann(_1), _1, _2, type_wildcard(get_ann(_1)), _3})
+    , ?RULE(id(), args(), tok(':'), type(), guarded_fundefs(), {letfun, get_ann(_1), _1, _2, _4, _5})
    ]).

 args() -> paren_list(pattern()).
@@ -208,6 +230,9 @@ arg() -> choice(
    ?RULE(id(),                   {arg, get_ann(_1), _1, type_wildcard(get_ann(_1))}),
    ?RULE(id(), tok(':'), type(), {arg, get_ann(_1), _1, _3})).

+letpat() ->
+    ?RULE(keyword('('), id(), tok('='), pattern(), tok(')'), {letpat, get_ann(_1), _2, _4}).
+
 %% -- Types ------------------------------------------------------------------

 type_vars() -> paren_list(tvar()).
@@ -254,7 +279,8 @@ body() ->

 stmt() ->
    ?LAZY_P(choice(
-    [ expr()
+    [ using()
+    , expr()
    , letdecl()
    , {switch, keyword(switch), parens(expr()), maybe_block(branch())}
    , {'if', keyword('if'), parens(expr()), body()}
@@ -263,7 +289,13 @@ stmt() ->
    ])).

 branch() ->
-    ?RULE(pattern(), keyword('=>'), body(), {'case', _2, _1, _3}).
+    ?RULE(pattern(), guarded_branches(), {'case', get_ann(lists:nth(1, _2)), _1, _2}).
+
+guarded_branches() ->
+    choice(
+    [ ?RULE(keyword('=>'), body(), [{guarded, _1, [], _2}])
+    , maybe_block(?RULE(tok('|'), comma_sep(expr()), keyword('=>'), body(), {guarded, _3, _2, _4}))
+    ]).

 pattern() ->
    ?LET_P(E, expr(), parse_pattern(E)).
@@ -311,6 +343,7 @@ exprAtom() ->
        , ?RULE(keyword('['), Expr, token('|'), comma_sep(comprehension_exp()), tok(']'), list_comp_e(_1, _2, _4))
        , ?RULE(tok('['), Expr, binop('..'), Expr, tok(']'), _3(_2, _4))
        , ?RULE(keyword('('), comma_sep(Expr), tok(')'), tuple_e(_1, _2))
+        , letpat()
        ])
    end).

@@ -571,6 +604,8 @@ tuple_e(Ann, Exprs)   -> {tuple, Ann, Exprs}.
 list_comp_e(Ann, Expr, Binds) -> {list_comp, Ann, Expr, Binds}.

 -spec parse_pattern(aeso_syntax:expr()) -> aeso_parse_lib:parser(aeso_syntax:pat()).
+parse_pattern({letpat, Ann, Id, Pat}) ->
+    {letpat, Ann, Id, parse_pattern(Pat)};
 parse_pattern({app, Ann, Con = {'::', _}, Es}) ->
    {app, Ann, Con, lists:map(fun parse_pattern/1, Es)};
 parse_pattern({app, Ann, {'-', _}, [{int, _, N}]}) ->
@@ -212,8 +212,10 @@ name({typed, _, Name, _}) -> name(Name).
 -spec letdecl(string(), aeso_syntax:letbind()) -> doc().
 letdecl(Let, {letval, _, P, E}) ->
    block_expr(0, hsep([text(Let), expr(P), text("=")]), E);
-letdecl(Let, {letfun, _, F, Args, T, E}) ->
-    block_expr(0, hsep([text(Let), typed(beside(name(F), expr({tuple, [], Args})), T), text("=")]), E).
+letdecl(Let, {letfun, _, F, Args, T, [GuardedBody]}) ->
+    beside(hsep([text(Let), typed(beside(name(F), expr({tuple, [], Args})), T)]), guarded_body(GuardedBody, "="));
+letdecl(Let, {letfun, _, F, Args, T, GuardedBodies}) ->
+    block(hsep([text(Let), typed(beside(name(F), expr({tuple, [], Args})), T)]), above(lists:map(fun(GB) -> guarded_body(GB, "=") end, GuardedBodies))).

 -spec args([aeso_syntax:arg()]) -> doc().
 args(Args) ->
@@ -299,6 +301,8 @@ tuple_type(Factors) ->
      ]).

 -spec expr_p(integer(), aeso_syntax:arg_expr()) -> doc().
+expr_p(P, {letpat, _, Id, Pat}) ->
+    paren(P > 100, follow(hsep(expr(Id), text("=")), expr(Pat)));
 expr_p(P, {named_arg, _, Name, E}) ->
    paren(P > 100, follow(hsep(expr(Name), text("=")), expr(E)));
 expr_p(P, {lam, _, Args, E}) ->
@@ -480,8 +484,18 @@ elim1(Proj={proj, _, _})      -> beside(text("."), elim(Proj));
 elim1(Get={map_get, _, _})    -> elim(Get);
 elim1(Get={map_get, _, _, _}) -> elim(Get).

-alt({'case', _, Pat, Body}) ->
-    block_expr(0, hsep(expr(Pat), text("=>")), Body).
+alt({'case', _, Pat, [GuardedBody]}) ->
+    beside(expr(Pat), guarded_body(GuardedBody, "=>"));
+alt({'case', _, Pat, GuardedBodies}) ->
+    block(expr(Pat), above(lists:map(fun(GB) -> guarded_body(GB, "=>") end, GuardedBodies))).
+
+guarded_body({guarded, _, Guards, Body}, Then) ->
+    block_expr(0, hsep(guards(Guards), text(Then)), Body).
+
+guards([]) ->
+    text("");
+guards(Guards) ->
+    hsep([text(" |"), par(punctuate(text(","), lists:map(fun expr/1, Guards)), 0)]).

 block_expr(_, Header, {block, _, Ss}) ->
    block(Header, statements(Ss));
@@ -45,7 +45,7 @@ lexer() ->

    Keywords = ["contract", "include", "let", "switch", "type", "record", "datatype", "if", "elif", "else", "function",
                "stateful", "payable", "true", "false", "mod", "public", "entrypoint", "private", "indexed", "namespace",
-                "interface", "main"
+                "interface", "main", "using", "as", "for", "hiding"
               ],
    KW = string:join(Keywords, "|"),

@@ -35,6 +35,9 @@
 -type qcon() :: {qcon, ann(), [name()]}.
 -type tvar() :: {tvar, ann(), name()}.

+-type namespace_alias() :: none | con().
+-type namespace_parts() :: none | {for, [id()]} | {hiding, [id()]}.
+
 -type decl() :: {contract_main, ann(), con(), [decl()]}
              | {contract_child, ann(), con(), [decl()]}
              | {contract_interface, ann(), con(), [decl()]}
@@ -44,6 +47,7 @@
              | {type_def, ann(), id(), [tvar()], typedef()}
              | {fun_clauses, ann(), id(), type(), [letfun() | fundecl()]}
              | {block, ann(), [decl()]}
+              | {using, ann(), con(), namespace_alias(), namespace_parts()}
              | fundecl()
              | letfun()
              | letval(). % Only for error msgs
@@ -52,9 +56,12 @@

 -type pragma() :: {compiler, '==' | '<' | '>' | '=<' | '>=', compiler_version()}.

+-type guard() :: expr().
+-type guarded_expr() :: {guarded, ann(), [guard()], expr()}.

 -type letval()  :: {letval, ann(), pat(), expr()}.
-type letfun()  :: {letfun, ann(), id(), [pat()], type(), expr()}.
+-type letfun()  :: {letfun, ann(), id(), [pat()], type(), [guarded_expr(),...]}.
+-type letpat()  :: {letpat, ann(), id(), pat()}.
 -type fundecl() :: {fun_decl, ann(), id(), type()}.

 -type letbind()
@@ -119,7 +126,8 @@
     | {block, ann(), [stmt()]}
     | {op(), ann()}
     | id() | qid() | con() | qcon()
-     | constant().
+     | constant()
+     | letpat().

 -type record_or_map() :: record | map | record_or_map_error.

@@ -140,7 +148,7 @@
 -type stmt() :: letbind()
              | expr().

-type alt() :: {'case', ann(), pat(), expr()}.
+-type alt() :: {'case', ann(), pat(), [guarded_expr(),...]}.

 -type lvalue() :: nonempty_list(elim()).

@@ -153,6 +161,7 @@
             | {list, ann(), [pat()]}
             | {typed, ann(), pat(), type()}
             | {record, ann(), [field(pat())]}
+             | letpat()
             | constant()
             | con()
             | id().
@@ -41,15 +41,15 @@ fold(Alg = #alg{zero = Zero, plus = Plus, scoped = Scoped}, Fun, K, X) ->
    Top = Fun(K, X),
    Rec = case X of
            %% lists (bound things in head scope over tail)
-            [A | As]                 -> Scoped(Same(A), Same(As));
+            [A | As]                      -> Scoped(Same(A), Same(As));
            %% decl()
-            {contract, _, _, Ds}     -> Decl(Ds);
-            {namespace, _, _, Ds}    -> Decl(Ds);
-            {type_def, _, I, _, D}   -> Plus(BindType(I), Decl(D));
-            {fun_decl, _, _, T}      -> Type(T);
-            {letval, _, P, E}        -> Scoped(BindExpr(P), Expr(E));
-            {letfun, _, F, Xs, T, E} -> Sum([BindExpr(F), Type(T), Expr(Xs ++ [E])]);
-            {fun_clauses, _, _, T, Cs} -> Sum([Type(T) | [Decl(C) || C <- Cs]]);
+            {contract, _, _, Ds}          -> Decl(Ds);
+            {namespace, _, _, Ds}         -> Decl(Ds);
+            {type_def, _, I, _, D}        -> Plus(BindType(I), Decl(D));
+            {fun_decl, _, _, T}           -> Type(T);
+            {letval, _, P, E}             -> Scoped(BindExpr(P), Expr(E));
+            {letfun, _, F, Xs, T, GEs} -> Sum([BindExpr(F), Type(T), Expr(Xs ++ GEs)]);
+            {fun_clauses, _, _, T, Cs}    -> Sum([Type(T) | [Decl(C) || C <- Cs]]);
            %% typedef()
            {alias_t, T}    -> Type(T);
            {record_t, Fs}  -> Type(Fs);
@@ -88,13 +88,15 @@ fold(Alg = #alg{zero = Zero, plus = Plus, scoped = Scoped}, Fun, K, X) ->
            {map_get, _, A, B}     -> Expr([A, B]);
            {map_get, _, A, B, C}  -> Expr([A, B, C]);
            {block, _, Ss}         -> Expr(Ss);
+            {letpat, _, X, P}      -> Plus(BindExpr(X), Expr(P));
+            {guarded, _, Gs, E}    -> Expr([E | Gs]);
            %% field()
            {field, _, LV, E}    -> Expr([LV, E]);
            {field, _, LV, _, E} -> Expr([LV, E]);
            %% arg()
            {arg, _, Y, T} -> Plus(BindExpr(Y), Type(T));
            %% alt()
-            {'case', _, P, E} -> Scoped(BindExpr(P), Expr(E));
+            {'case', _, P, GEs} -> Scoped(BindExpr(P), Expr(GEs));
            %% elim()
            {proj, _, _}    -> Zero;
            {map_get, _, E} -> Expr(E);
@@ -120,10 +120,98 @@ from_fate({constr_t, _, Con, Types}, Args)
        when length(Types) == length(Args) ->
    {app, [], Con, [ from_fate(Type, Arg)
                     || {Type, Arg} <- lists:zip(Types, Args) ]};
+from_fate({qid, _, QType}, Val) ->
+    from_fate_builtin(QType, Val);
 from_fate(_Type, _Data) ->
    throw(cannot_translate_to_sophia).


+from_fate_builtin(QType, Val) ->
+    Con = fun([Name | _] = Names) when is_list(Name) -> {qcon, [], Names};
+             (Name) -> {con, [], Name} end,
+    App = fun(Name, []) -> Con(Name);
+             (Name, Value) -> {app, [], Con(Name), Value} end,
+    Chk = fun(Type, Value) -> from_fate(Type, Value) end,
+    Int = {id, [], "int"},
+    Str = {id, [], "string"},
+    Adr = {id, [], "address"},
+    Hsh = {bytes_t, [], 32},
+    Qid = fun(Name) -> {qid, [], Name} end,
+    Map = fun(KT, VT) -> {app_t, [], {id, [], "map"}, [KT, VT]} end,
+    ChainTxArities = [3, 0, 0, 0, 0, 0, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 2, 0],
+
+    case {QType, Val} of
+        {["Chain", "ttl"], {variant, [1, 1], 0, {X}}} -> App("RelativeTTL", [Chk(Int, X)]);
+        {["Chain", "ttl"], {variant, [1, 1], 1, {X}}} -> App("FixedTTL", [Chk(Int, X)]);
+
+        {["AENS", "name"], {variant, [3], 0, {Addr, TTL, Ptrs}}} ->
+            App(["AENS","Name"], [Chk(Adr, Addr), Chk(Qid(["Chain", "ttl"]), TTL),
+                              Chk(Map(Str, Qid(["AENS", "pointee"])), Ptrs)]);
+
+        {["AENS", "pointee"], {variant, [1, 1, 1, 1], 0, {Addr}}} ->
+            App(["AENS","AccountPt"], [Chk(Adr, Addr)]);
+        {["AENS", "pointee"], {variant, [1, 1, 1, 1], 1, {Addr}}} ->
+            App(["AENS","OraclePt"], [Chk(Adr, Addr)]);
+        {["AENS", "pointee"], {variant, [1, 1, 1, 1], 2, {Addr}}} ->
+            App(["AENS","ContractPt"], [Chk(Adr, Addr)]);
+        {["AENS", "pointee"], {variant, [1, 1, 1, 1], 3, {Addr}}} ->
+            App(["AENS","ChannelPt"], [Chk(Adr, Addr)]);
+
+        {["Chain", "ga_meta_tx"], {variant, [2], 0, {Addr, X}}} ->
+            App(["Chain","GAMetaTx"], [Chk(Adr, Addr), Chk(Int, X)]);
+
+        {["Chain", "paying_for_tx"], {variant, [2], 0, {Addr, X}}} ->
+            App(["Chain","PayingForTx"], [Chk(Adr, Addr), Chk(Int, X)]);
+
+        {["Chain", "base_tx"], {variant, ChainTxArities, 0, {Addr, Fee, Payload}}} ->
+            App(["Chain","SpendTx"], [Chk(Adr, Addr), Chk(Int, Fee), Chk(Str, Payload)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 1, {}}} ->
+            App(["Chain","OracleRegisterTx"], []);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 2, {}}} ->
+            App(["Chain","OracleQueryTx"], []);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 3, {}}} ->
+            App(["Chain","OracleResponseTx"], []);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 4, {}}} ->
+            App(["Chain","OracleExtendTx"], []);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 5, {}}} ->
+            App(["Chain","NamePreclaimTx"], []);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 6, {Name}}} ->
+            App(["Chain","NameClaimTx"], [Chk(Str, Name)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 7, {NameHash}}} ->
+            App(["Chain","NameUpdateTx"], [Chk(Hsh, NameHash)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 8, {NameHash}}} ->
+            App(["Chain","NameRevokeTx"], [Chk(Hsh, NameHash)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 9, {NewOwner, NameHash}}} ->
+            App(["Chain","NameTransferTx"], [Chk(Adr, NewOwner), Chk(Hsh, NameHash)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 10, {Addr}}} ->
+            App(["Chain","ChannelCreateTx"], [Chk(Adr, Addr)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 11, {Addr, Amount}}} ->
+            App(["Chain","ChannelDepositTx"], [Chk(Adr, Addr), Chk(Int, Amount)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 12, {Addr, Amount}}} ->
+            App(["Chain","ChannelWithdrawTx"], [Chk(Adr, Addr), Chk(Int, Amount)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 13, {Addr}}} ->
+            App(["Chain","ChannelForceProgressTx"], [Chk(Adr, Addr)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 14, {Addr}}} ->
+            App(["Chain","ChannelCloseMutualTx"], [Chk(Adr, Addr)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 15, {Addr}}} ->
+            App(["Chain","ChannelCloseSoloTx"], [Chk(Adr, Addr)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 16, {Addr}}} ->
+            App(["Chain","ChannelSlashTx"], [Chk(Adr, Addr)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 17, {Addr}}} ->
+            App(["Chain","ChannelSettleTx"], [Chk(Adr, Addr)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 18, {Addr}}} ->
+            App(["Chain","ChannelSnapshotSoloTx"], [Chk(Adr, Addr)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 19, {Amount}}} ->
+            App(["Chain","ContractCreateTx"], [Chk(Int, Amount)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 20, {Addr, Amount}}} ->
+            App(["Chain","ContractCallTx"], [Chk(Adr, Addr), Chk(Int, Amount)]);
+        {["Chain", "base_tx"], {variant, ChainTxArities, 21, {}}} ->
+            App(["Chain","GAAttachTx"], []);
+
+        _ ->
+            throw(cannot_translate_to_sophia)
+    end.
+
 make_bits(N) ->
    Id = fun(F) -> {qid, [], ["Bits", F]} end,
    if N < 0 -> make_bits(Id("clear"), Id("all"), 0, bnot N);
@@ -1,6 +1,6 @@
 {application, aesophia,
 [{description, "Compiler for Aeternity Sophia language"},
-  {vsn, "6.0.2"},
+  {vsn, "6.1.0"},
  {registered, []},
  {applications,
   [kernel,
@@ -33,7 +33,7 @@ test_cases(1) ->
 			    stateful => true,
                            payable  => true}]}},
    DecACI = <<"payable main contract C =\n"
-	       "  payable entrypoint a : (int) => int\n">>,
+	       "  payable stateful entrypoint a : (int) => int\n">>,
    {Contract,MapACI,DecACI};

 test_cases(2) ->
@@ -59,7 +59,7 @@ calldata_aci_test_() ->
        end} || {ContractName, Fun, Args} <- compilable_contracts()].

 parse_args(Fun, Args) ->
-    [{contract_main, _, _, [{letfun, _, _, _, _, {app, _, _, AST}}]}] =
+    [{contract_main, _, _, [{letfun, _, _, _, _, [{guarded, _, [], {app, _, _, AST}}]}]}] =
        aeso_parser:string("main contract Temp = function foo() = " ++ Fun ++ "(" ++ string:join(Args, ", ") ++ ")"),
    strip_ann(AST).

@@ -112,8 +112,28 @@ compilable_contracts() ->
     {"funargs", "traffic_light", ["Green"]},
     {"funargs", "traffic_light", ["Pantone(12)"]},
     {"funargs", "tuples", ["()"]},
-     %% TODO {"funargs", "due", ["FixedTTL(1020)"]},
+     {"funargs", "due", ["FixedTTL(1020)"]},
     {"funargs", "singleton_rec", ["{x = 1000}"]},
+     {"funargs", "aens_name", ["AENS.Name(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR, RelativeTTL(100), {[\"pt1\"] = AENS.AccountPt(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR)})"]},
+     {"funargs", "aens_pointee", ["AENS.AccountPt(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR)"]},
+     {"funargs", "aens_pointee", ["AENS.OraclePt(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR)"]},
+     {"funargs", "aens_pointee", ["AENS.ContractPt(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR)"]},
+     {"funargs", "aens_pointee", ["AENS.ChannelPt(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR)"]},
+     {"funargs", "chain_ga_meta_tx", ["Chain.GAMetaTx(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR, 42)"]},
+     {"funargs", "chain_paying_for_tx", ["Chain.PayingForTx(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR, 42)"]},
+     {"funargs", "chain_base_tx", ["Chain.SpendTx(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR, 42,\"foo\")"]},
+     {"funargs", "chain_base_tx", ["Chain.ContractCreateTx(12234)"]},
+     {"funargs", "chain_base_tx", ["Chain.ContractCallTx(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR, 12234)"]},
+     {"funargs", "chain_base_tx", ["Chain.OracleRegisterTx"]},
+     {"funargs", "chain_base_tx", ["Chain.OracleQueryTx"]},
+     {"funargs", "chain_base_tx", ["Chain.OracleResponseTx"]},
+     {"funargs", "chain_base_tx", ["Chain.OracleExtendTx"]},
+     {"funargs", "chain_base_tx", ["Chain.NamePreclaimTx"]},
+     {"funargs", "chain_base_tx", ["Chain.NameClaimTx(\"acoolname.chain\")"]},
+     {"funargs", "chain_base_tx", ["Chain.NameUpdateTx(#ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)"]},
+     {"funargs", "chain_base_tx", ["Chain.NameRevokeTx(#ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)"]},
+     {"funargs", "chain_base_tx", ["Chain.NameTransferTx(ak_2dATVcZ9KJU5a8hdsVtTv21pYiGWiPbmVcU1Pz72FFqpk9pSRR, #ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)"]},
+     {"funargs", "chain_base_tx", ["Chain.GAAttachTx"]},
     {"variant_types", "init", []},
     {"basic_auth", "init", []},
     {"address_literals", "init", []},
@@ -200,6 +200,9 @@ compilable_contracts() ->
     "clone_simple",
     "create",
     "child_contract_init_bug",
+     "using_namespace",
+     "assign_patterns",
+     "patterns_guards",
     "test" % Custom general-purpose test file. Keep it last on the list.
    ].

@@ -235,6 +238,7 @@ failing_contracts() ->
    , ?PARSE_ERROR(vsemi,  [<<?Pos(3, 3) "Unexpected indentation. Did you forget a '}'?">>])
    , ?PARSE_ERROR(vclose, [<<?Pos(4, 3) "Unexpected indentation. Did you forget a ']'?">>])
    , ?PARSE_ERROR(indent_fail, [<<?Pos(3, 2) "Unexpected token 'entrypoint'.">>])
+    , ?PARSE_ERROR(assign_pattern_to_pattern, [<<?Pos(3, 22) "Unexpected token '='.">>])

    %% Type errors
    , ?TYPE_ERROR(name_clash,
@@ -781,6 +785,38 @@ failing_contracts() ->
                   [<<?Pos(1,6)
                      "Only one main contract can be defined.">>
                   ])
+    , ?TYPE_ERROR(using_namespace_ambiguous_name,
+                  [ <<?Pos(2,3)
+                      "Ambiguous name: Xa.f at line 2, column 3\nXb.f at line 5, column 3">>
+                  , <<?Pos(13,23)
+                      "Unbound variable A.f at line 13, column 23">>
+                  ])
+    , ?TYPE_ERROR(using_namespace_wrong_scope,
+                  [ <<?Pos(19,5)
+                      "Unbound variable f at line 19, column 5">>
+                  , <<?Pos(21,23)
+                      "Unbound variable f at line 21, column 23">>
+                  ])
+    , ?TYPE_ERROR(using_namespace_undefined,
+                  [<<?Pos(2,3)
+                     "Cannot use undefined namespace MyUndefinedNamespace">>
+                  ])
+    , ?TYPE_ERROR(using_namespace_undefined_parts,
+                  [<<?Pos(5,3)
+                     "The namespace Nsp does not define the following names: a">>
+                  ])
+    , ?TYPE_ERROR(using_namespace_hidden_parts,
+                  [<<?Pos(8,23)
+                     "Unbound variable g at line 8, column 23">>
+                  ])
+    , ?TYPE_ERROR(stateful_pattern_guard,
+                  [<<?Pos(8,12)
+                     "Cannot reference stateful function g (at line 8, column 12) in a pattern guard.">>
+                  ])
+    , ?TYPE_ERROR(non_boolean_pattern_guard,
+                  [<<?Pos(4,24)
+                     "Cannot unify string\n         and bool\nwhen checking the type of the expression at line 4, column 24\n  \"y\" : string\nagainst the expected type\n  bool">>
+                  ])
    ].

 -define(Path(File), "code_errors/" ??File).
@@ -17,7 +17,7 @@ simple_contracts_test_() ->
            ?assertMatch(
                [{contract_main, _, {con, _, "Identity"},
                    [{letfun, _, {id, _, "id"}, [{id, _, "x"}], {id, _, "_"},
-                        {id, _, "x"}}]}], parse_string(Text)),
+                        [{guarded, _, [], {id, _, "x"}}]}]}], parse_string(Text)),
            ok
       end},
      {"Operator precedence test.",
@@ -0,0 +1,4 @@
+contract AssignPatternToPattern =
+    entrypoint f() =
+        let x::(t::z = y) = [1, 2, 3]
+        (x + t)::y
@@ -0,0 +1,16 @@
+include "List.aes"
+
+contract AssignPatterns =
+
+  entrypoint test() = foo([1, 0, 2], (2, Some(3)), Some([4, 5]))
+
+  entrypoint foo(xs : list(int), p : int * option(int), some : option(list(int))) =
+    let x::(t = y::_)  = xs
+    let z::_ = t
+
+    let (a, (o = Some(b)))  = p
+
+    let Some((f = g::_)) = some
+    g + List.get(1, f)
+
+    x + y + z + a + b
@@ -50,3 +50,10 @@ contract FunctionArguments =

  entrypoint singleton_rec(r : singleton_r) =
    r.x
+
+  entrypoint aens_name(n : AENS.name) = true
+  entrypoint aens_pointee(p : AENS.pointee) = true
+
+  entrypoint chain_ga_meta_tx(tx : Chain.ga_meta_tx) = true
+  entrypoint chain_paying_for_tx(tx : Chain.paying_for_tx) = true
+  entrypoint chain_base_tx(tx : Chain.base_tx) = true
@@ -0,0 +1,4 @@
+contract C =
+  type state = int
+
+  entrypoint init(x) | "y" = 1
@@ -0,0 +1,19 @@
+include "List.aes"
+
+contract C =
+  type state = int
+
+  entrypoint init() = f([1, 2, 3, 4])
+
+  function
+    f(x::[])
+      | x > 1, x < 10 = 1
+      | x < 1 = 9
+    f(x::y::[]) = 2
+    f(x::y::z) = switch(z)
+      [] => 4
+      a::[]
+        | a > 10, a < 20 => 5
+        | a > 5 => 8
+      b | List.length(b) > 5 => 6
+      c => 7
@@ -0,0 +1,10 @@
+contract C =
+  type state = int
+
+  entrypoint init() = f(4)
+
+  function
+    f(x) | x > 0 = 1
+    f(x) | g(x) = 2
+
+  stateful function g(x) = x < 0
@@ -0,0 +1,36 @@
+include "Option.aes"
+include "Pair.aes"
+include "String.aes"
+include "Triple.aes"
+
+using Pair
+using Triple hiding [fst, snd]
+
+namespace Nsp =
+  using Option
+
+  function h() =
+    let op = Some((2, 3, 4))
+    if (is_some(op))
+      thd(force(op)) == 4
+    else
+      false
+
+contract Cntr =
+  using Nsp
+
+  entrypoint init() = ()
+
+  function f() =
+    let p = (1, 2)
+    if (h())
+      fst(p)
+    else
+      snd(p)
+
+  function g() =
+    using String for [concat]
+
+    let s1 = "abc"
+    let s2 = "def"
+    concat(s1, s2)
@@ -0,0 +1,13 @@
+namespace Xa =
+  function f() = 1
+
+namespace Xb =
+  function f() = 2
+
+contract Cntr =
+  using Xa as A
+  using Xb as A
+
+  type state = int
+
+  entrypoint init() = A.f()
@@ -0,0 +1,8 @@
+namespace Nsp =
+  function f() = 1
+  function g() = 2
+
+contract Cntr =
+  using Nsp for [f]
+
+  entrypoint init() = g()
@@ -0,0 +1,4 @@
+contract C =
+  using MyUndefinedNamespace
+
+  entrypoint init() = ()
@@ -0,0 +1,7 @@
+namespace Nsp =
+  function f() = 1
+
+contract Cntr =
+  using Nsp for [a]
+
+  entrypoint init() = f()
@@ -0,0 +1,21 @@
+namespace Nsp1 =
+  function f() = 1
+
+namespace Nsp2 =
+  using Nsp1
+
+  function g() = 1
+
+contract Cntr =
+  using Nsp2
+
+  type state = int
+
+  function x() =
+    using Nsp1
+    f()
+
+  function y() =
+    f()
+
+  entrypoint init() = f()
Author	SHA1	Message	Date
Gaith Hallak	5ad5270e38	Bump version to 6.1.0 and fix CHANGELOG (#348 )	2021-10-20 12:42:48 +03:00
Gaith Hallak	a982f25262	Pattern guards for functions and switch statements (#339 ) * Add case guards to parser * Add pattern guards to infer types and fcode generation * Add functions guards * Add test for patterns guards * Update docs * Update CHANGELOG.md * Remove stateful context from Env for guards * Elaborate on guards * Add failing test for stateful pattern guards * Implement multiple guards * Fix tests * Disable aevm related tests * Split the sentence before if and otherwise * Fix type in docs * Implement multiple exprs in the same guard * Fix pretty printing * Change tests to include multiple guards * Add test for non-boolean guards * Desugar clauses with guards * Fix incomplete patterns bug * Fix docs * Compile to icode when no guards are used * Revert "Disable aevm related tests" This reverts commit e828099bd97dffe11438f2e48f3a92ce3641e85b.	2021-10-20 11:04:00 +03:00
Hans Svensson	20cab3ae57	Merge pull request #347 from marc0olo/chore/update-mkdocs-version chore: mkdocs v1.2.3	2021-10-18 10:33:10 +02:00
marc0olo	1ffb20178c	chore: mkdocs v1.2.3	2021-10-15 12:03:46 +02:00
Hans Svensson	6d79d2d558	GH344 - Add builtin types in decoder (#345 ) * Only use basic types in type_env * Add builtin types to the calldata/result decoder for FATE	2021-09-30 19:11:00 +02:00
Hans Svensson	24c579a5d3	Merge pull request #342 from aeternity/fix_aci_rendering Don't forget stateful when rendering the ACI	2021-09-24 14:21:42 +02:00
Hans Svensson	1be24c94c5	Don't forget stateful when rendering the ACI	2021-09-20 14:50:16 +02:00
Hans Svensson	ebb1f9ecf9	Merge pull request #340 from aeternity/add_bitwise_stdlib Add Bitwise.aes to stdlib	2021-09-16 10:49:00 +02:00
Hans Svensson	9cb3158dfd	Fix documentation and comments	2021-09-12 16:24:08 +02:00
Hans Svensson	becafe4001	Add Bitwise.aes to stdlib	2021-09-12 14:57:45 +02:00
Gaith Hallak	e8a171dc45	Allow assigning patterns to variables (#336 ) * Change syntax tree and parser * Add assign pattern to type inference * Use check_expr instead of hard-coded type * Add fcode generation for assign pattern * Implement rename_spat for assign pattern * Add tests * Update CHANGELOG.md * Update docs and changelog * Add letpat to aeso_syntax_utils:fold * Use Plus instead of Scoped	2021-09-11 16:18:30 +02:00
Gaith Hallak	a7b7aafced	Implement loading namespaces with the `using` keyword (#338 ) * Add using namespace as to scanner and parser * Change the alias from id() to con() * Add using namespace to AST type inference * Allow using namespace to appear in the top level * Allow using namespace to appear inside functions * Add a compiler test for using namespace * Handle name collisions * Implement mk_error for ambiguous_name * Add failing test for ambiguous names * Limit the scope of the used namespaces * Add test for wrong scope of using namespace * Use a single using declaration * Split long line * Forbid using undefined namespaces * Add a test for using undefined namespaces * Change the type of used_namespaces * Add using namespace parts to scanner and parser * Add using namespace parts to ast type inference * Add tests for using namespace parts * Update CHANGELOG.md * Code cleaning * Update the docs * Update the docs about the same alias for multiple namespaces	2021-09-07 17:45:28 +03:00
Marco Walz	262452fb70	Feature/mkdocs with versioning (#333 ) * docs: restructuring & introduction of mkdocs with versioning provided by mike * docs: ad repositories section to sophia examples * docs: refactoring and consistent naming of æternity * docs: hint for new file destination * docs: revert capital letter * docs: accept proposed changes * docs: fix anchors in stdlib	2021-08-27 17:46:18 +03:00
Gaith Hallak	3029bf31cb	Implement `Set` stdlib (#335 ) * Implement Set stdlib * Rename an argument of the function Set.fold * Add docs for Set stdlib * Correct the usage of articles in the docs * Fix bug * Fix the link to Set stdlib section Co-authored-by: Radosław Rowicki <35342116+radrow@users.noreply.github.com>	2021-08-07 10:08:45 +02:00
Radosław Rowicki	4896ad3b36	Add Option.force_msg (#328 ) * Add Option.force_msg * CHANGELOG update	2021-08-03 11:39:53 +02:00
Hans Svensson	b20b9c5df5	Merge pull request #329 from callbay/fix_var_in_example Fix var in example	2021-07-26 12:04:55 +02:00
Frank Feng	d793660545	Fix var in example	2021-07-24 16:46:13 +08:00
Hans Svensson	4957d01e9e	Merge pull request #327 from aeternity/fix_doc Fix stdlib doc	2021-07-13 20:40:49 +02:00
Hans Svensson	9d76e6186a	Fix stdlib doc	2021-07-13 20:01:54 +02:00