changelog

* Improve independence analysis

* Changelog updated

CHANGELOG.md

@@ -7,8 +7,34 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Added
 ### Changed
+- Names of lifted lambdas now consist of parent function's name and their
+  position in the source code.
 ### Removed
 ### Fixed
+- Lifted lambdas get their names assigned deterministically.
+
+## [7.3.0]
+### Fixed
+- Fixed a bug with polymorphism that allowed functions with the same name but different type to be considered as implementations for their corresponding interface function.
+- Fixed a bug in the byte code optimization that incorrectly reordered dependent instructions.
+
+## [7.2.1]
+### Fixed
+- Fixed bugs with the newly added debugging symbols
+
+## [7.2.0]
+### Added
+- Toplevel compile-time constants
+  ```
+  namespace N =
+    let nc = 1
+  contract C =
+    let cc = 2
+  ```
+- API functions for encoding/decoding Sophia values to/from FATE.
+### Removed
+- Remove the mapping from variables to FATE registers from the compilation output.
+### Fixed
 - Warning about unused include when there is no include.
 
 ## [7.1.0]
@@ -381,7 +407,10 @@ 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/v7.1.0...HEAD
+[Unreleased]: https://github.com/aeternity/aesophia/compare/v7.3.0...HEAD
+[7.3.0]: https://github.com/aeternity/aesophia/compare/v7.2.1...v7.3.0
+[7.2.1]: https://github.com/aeternity/aesophia/compare/v7.2.0...v7.2.1
+[7.2.0]: https://github.com/aeternity/aesophia/compare/v7.1.0...v7.2.0
 [7.1.0]: https://github.com/aeternity/aesophia/compare/v7.0.1...v7.1.0
 [7.0.1]: https://github.com/aeternity/aesophia/compare/v7.0.0...v7.0.1
 [7.0.0]: https://github.com/aeternity/aesophia/compare/v6.1.0...v7.0.0

docs/aeso_compiler.md

@@ -53,8 +53,6 @@ The **pp_** options all print to standard output the following:
 
 The option `include_child_contract_symbols` includes the symbols of child contracts functions in the generated fate code. It is turned off by default to avoid making contracts bigger on chain.
 
-The option `debug_info` includes information related to debugging in the compiler output. Currently this option only includes the mapping from variables to registers.
-
 #### Options to control which compiler optimizations should run:
 
 By default all optimizations are turned on, to disable an optimization, it should be

docs/sophia_features.md

@@ -573,6 +573,32 @@ contract C =
 
 A hole expression found in the example above will generate the error `` Found a hole of type `(int) => int` ``. This says that the compiler expects a function from `int` to `int` in place of the `???` placeholder.
 
+## Constants
+
+Constants in Sophia are contract-level bindings that can be used in either contracts or namespaces. The value of a constant can be a literal, another constant, or arithmetic operations applied to other constants. Lists, tuples, maps, and records can also be used to define a constant as long as their elements are also constants.
+
+The following visibility rules apply to constants:
+*  Constants defined inside a contract are private in that contract. Thus, cannot be accessed through instances of their defining contract.
+* Constants defined inside a namespace are public. Thus, can be used in other contracts or namespaces.
+* Constants cannot be defined inside a contract interface.
+
+When a constant is shadowed, it can be accessed using its qualified name:
+
+```
+contract C =
+  let c = 1
+  entrypoint f() =
+    let c = 2
+    c + C.c  // the result is 3
+```
+
+The name of the constant must be an id; therefore, no pattern matching is allowed when defining a constant:
+
+```
+contract C
+  let x::y::_ = [1,2,3]  // this will result in an error
+```
+
 ## Arithmetic
 
 Sophia integers (`int`) are represented by arbitrary-sized signed words and support the following

docs/sophia_stdlib.md

@@ -190,7 +190,7 @@ using the private key of the `owner` account for signing.
 ##### update
 ```
 AENS.update(owner : address, name : string, expiry : option(Chain.ttl), client_ttl : option(int),
-            new_ptrs : map(string, AENS.pointee), <signature : signature>) : unit
+            new_ptrs : option(map(string, AENS.pointee)), <signature : signature>) : unit
 ```
 
 Updates the name. If the optional parameters are set to `None` that parameter
@@ -470,38 +470,6 @@ Chain.block_height : int"
 The height of the current block (i.e. the block in which the current call will be included).
 
 
-##### coinbase
-```
-Chain.coinbase : address
-```
-
-The address of the account that mined the current block.
-
-
-##### timestamp
-```
-Chain.timestamp : int
-```
-
-The timestamp of the current block (unix time, milliseconds).
-
-
-##### difficulty
-```
-Chain.difficulty : int
-```
-
-The difficulty of the current block.
-
-
-##### gas
-```
-Chain.gas_limit : int
-```
-
-The gas limit of the current block.
-
-
 ##### bytecode_hash
 ```
 Chain.bytecode_hash : 'c => option(hash)
@@ -565,6 +533,7 @@ main contract Market =
 The typechecker must be certain about the created contract's type, so it is
 worth writing it explicitly as shown in the example.
 
+
 ##### clone
 ```
 Chain.clone : ( ref : 'c, gas : int, value : int, protected : bool, ...
@@ -623,11 +592,54 @@ implementation of the `init` function does not actually return `state`, but
 calls `put` instead. Moreover, FATE prevents even handcrafted calls to `init`.
 
 
+##### coinbase
+```
+Chain.coinbase : address
+```
+
+The address of the account that mined the current block.
+
+
+##### difficulty
+```
+Chain.difficulty : int
+```
+
+The difficulty of the current block.
+
+
 ##### event
 ```
 Chain.event(e : event) : unit
 ```
-Emits the event. To use this function one needs to define the `event` type as a `datatype` in the contract.
+
+Emits the event. To use this function one needs to define the `event` type as a
+`datatype` in the contract.
+
+
+##### gas\_limit
+```
+Chain.gas_limit : int
+```
+
+The gas limit of the current block.
+
+
+##### spend
+```
+Chain.spend(to : address, amount : int) : unit
+```
+
+Spend `amount` tokens to `to`. Will fail (and abort the contract) if contract
+doesn't have `amount` tokens to transfer, or, if `to` is not `payable`.
+
+
+##### timestamp
+```
+Chain.timestamp : int
+```
+
+The timestamp of the current block (unix time, milliseconds).
 
 
 ### Char

docs/sophia_syntax.md

@@ -104,6 +104,7 @@ Implement ::= ':' Sep1(Con, ',')
 Decl ::= 'type'     Id ['(' TVar* ')'] '=' TypeAlias
        | 'record'   Id ['(' TVar* ')'] '=' RecordType
        | 'datatype' Id ['(' TVar* ')'] '=' DataType
+       | 'let'      Id [':' Type]      '=' Expr
        | (EModifier* 'entrypoint' | FModifier* 'function') Block(FunDecl)
        | Using
 

rebar.config

@@ -2,8 +2,7 @@
 
 {erl_opts, [debug_info]}.
 
-{deps, [ {aebytecode, {git, "https://github.com/aeternity/aebytecode.git", {tag, "v3.2.0"}}}
-       , {getopt, "1.0.1"}
+{deps, [ {aebytecode, {git, "https://github.com/aeternity/aebytecode.git", {tag, "v3.3.0"}}}
        , {eblake2, "1.0.0"}
        , {jsx, {git, "https://github.com/talentdeficit/jsx.git", {tag, "2.8.0"}}}
        ]}.
@@ -14,7 +13,7 @@
             {base_plt_apps, [erts, kernel, stdlib, crypto, mnesia]}
            ]}.
 
-{relx, [{release, {aesophia, "7.1.0"},
+{relx, [{release, {aesophia, "7.3.0"},
          [aesophia, aebytecode, getopt]},
 
         {dev_mode, true},

rebar.lock

@@ -1,11 +1,11 @@
 {"1.2.0",
 [{<<"aebytecode">>,
   {git,"https://github.com/aeternity/aebytecode.git",
-       {ref,"2a0a397afad6b45da52572170f718194018bf33c"}},
+       {ref,"b38349274fc2bed98d7fe86877e6e1a2df302109"}},
   0},
  {<<"aeserialization">>,
   {git,"https://github.com/aeternity/aeserialization.git",
-       {ref,"eb68fe331bd476910394966b7f5ede7a74d37e35"}},
+       {ref,"177bf604b2a05e940f92cf00e96e6e269e708245"}},
   1},
  {<<"base58">>,
   {git,"https://github.com/aeternity/erl-base58.git",
@@ -16,7 +16,7 @@
   {git,"https://github.com/aeternity/enacl.git",
        {ref,"793ddb502f7fe081302e1c42227dca70b09f8e17"}},
   2},
- {<<"getopt">>,{pkg,<<"getopt">>,<<"1.0.1">>},0},
+ {<<"getopt">>,{pkg,<<"getopt">>,<<"1.0.1">>},1},
  {<<"jsx">>,
   {git,"https://github.com/talentdeficit/jsx.git",
        {ref,"3074d4865b3385a050badf7828ad31490d860df5"}},

src/aeso_ast_infer_types.erl

@@ -124,15 +124,18 @@
 
 -type variance() :: invariant | covariant | contravariant | bivariant.
 
--type fun_info()  :: {aeso_syntax:ann(), typesig() | type()}.
--type type_info() :: {aeso_syntax:ann(), typedef()}.
--type var_info()  :: {aeso_syntax:ann(), utype()}.
+-type fun_info()   :: {aeso_syntax:ann(), typesig() | type()}.
+-type type_info()  :: {aeso_syntax:ann(), typedef()}.
+-type const_info() :: {aeso_syntax:ann(), type()}.
+-type var_info()   :: {aeso_syntax:ann(), utype()}.
 
--type fun_env()  :: [{name(), fun_info()}].
--type type_env() :: [{name(), type_info()}].
+-type fun_env()   :: [{name(), fun_info()}].
+-type type_env()  :: [{name(), type_info()}].
+-type const_env() :: [{name(), const_info()}].
 
 -record(scope, { funs   = [] :: fun_env()
                , types  = [] :: type_env()
+               , consts = [] :: const_env()
                , access = public :: access()
                , kind   = namespace :: namespace | contract
                , ann    = [{origin, system}] :: aeso_syntax:ann()
@@ -151,7 +154,7 @@
     , in_pattern       = false              :: boolean()
     , in_guard         = false              :: boolean()
     , stateful         = false              :: boolean()
-    , unify_throws     = true               :: boolean()
+    , current_const    = none               :: none | aeso_syntax:id()
     , current_function = none               :: none | aeso_syntax:id()
     , what             = top                :: top | namespace | contract | contract_interface
     }).
@@ -183,9 +186,13 @@ pop_scope(Env) ->
 get_scope(#env{ scopes = Scopes }, Name) ->
     maps:get(Name, Scopes, false).
 
+-spec get_current_scope(env()) -> scope().
+get_current_scope(#env{ namespace = NS, scopes = Scopes }) ->
+    maps:get(NS, Scopes).
+
 -spec on_current_scope(env(), fun((scope()) -> scope())) -> env().
 on_current_scope(Env = #env{ namespace = NS, scopes = Scopes }, Fun) ->
-    Scope = maps:get(NS, Scopes),
+    Scope = get_current_scope(Env),
     Env#env{ scopes = Scopes#{ NS => Fun(Scope) } }.
 
 -spec on_scopes(env(), fun((scope()) -> scope())) -> env().
@@ -193,8 +200,8 @@ on_scopes(Env = #env{ scopes = Scopes }, Fun) ->
     Env#env{ scopes = maps:map(fun(_, Scope) -> Fun(Scope) end, Scopes) }.
 
 -spec bind_var(aeso_syntax:id(), utype(), env()) -> env().
-bind_var({id, Ann, X}, T, Env = #env{ vars = Vars }) ->
-    when_warning(warn_shadowing, fun() -> warn_potential_shadowing(Ann, X, Vars) end),
+bind_var({id, Ann, X}, T, Env) ->
+    when_warning(warn_shadowing, fun() -> warn_potential_shadowing(Env, Ann, X) end),
     Env#env{ vars = [{X, {Ann, T}} | Env#env.vars] }.
 
 -spec bind_vars([{aeso_syntax:id(), utype()}], env()) -> env().
@@ -247,6 +254,37 @@ bind_type(X, Ann, Def, Env) ->
                             Scope#scope{ types = [{X, {Ann, Def}} | Types] }
                           end).
 
+-spec bind_const(name(), aeso_syntax:ann(), type(), env()) -> env().
+bind_const(X, Ann, Type, Env) ->
+    case lookup_env(Env, term, Ann, [X]) of
+        false ->
+            on_current_scope(Env, fun(Scope = #scope{ consts = Consts }) ->
+                                    Scope#scope{ consts = [{X, {Ann, Type}} | Consts] }
+                                end);
+        _ ->
+            type_error({duplicate_definition, X, [Ann, aeso_syntax:get_ann(Type)]}),
+            Env
+    end.
+
+-spec bind_consts(env(), #{ name() => aeso_syntax:decl() }, [{acyclic, name()} | {cyclic, [name()]}], [aeso_syntax:decl()]) ->
+        {env(), [aeso_syntax:decl()]}.
+bind_consts(Env, _Consts, [], Acc) ->
+    {Env, lists:reverse(Acc)};
+bind_consts(Env, Consts, [{cyclic, Xs} | _SCCs], _Acc) ->
+    ConstDecls = [ maps:get(X, Consts) || X <- Xs ],
+    type_error({mutually_recursive_constants, lists:reverse(ConstDecls)}),
+    {Env, []};
+bind_consts(Env, Consts, [{acyclic, X} | SCCs], Acc) ->
+    case maps:get(X, Consts, undefined) of
+        Const = {letval, Ann, Id, _} ->
+            NewConst = {letval, _, {typed, _, _, Type}, _} = infer_const(Env, Const),
+            NewEnv = bind_const(name(Id), Ann, Type, Env),
+            bind_consts(NewEnv, Consts, SCCs, [NewConst | Acc]);
+        undefined ->
+            %% When a used id is not a letval, a type error will be thrown
+            bind_consts(Env, Consts, SCCs, Acc)
+    end.
+
 %% Bind state primitives
 -spec bind_state(env()) -> env().
 bind_state(Env) ->
@@ -312,11 +350,11 @@ bind_contract(Typing, {Contract, Ann, Id, _Impls, Contents}, Env)
     Sys         = [{origin, system}],
     TypeOrFresh = fun({typed, _, _, Type}) -> Type; (_) -> fresh_uvar(Sys) end,
     Fields      =
-        [ {field_t, AnnF, Entrypoint, contract_call_type(Type)}
+        [ {field_t, AnnF, Entrypoint, contract_call_type(aeso_syntax:set_ann(Sys, Type))}
           || {fun_decl, AnnF, Entrypoint, Type = {fun_t, _, _, _, _}} <- Contents ] ++
         [ {field_t, AnnF, Entrypoint,
            contract_call_type(
-             {fun_t, AnnF, [], [TypeOrFresh(Arg) || Arg <- Args], TypeOrFresh(Ret)})
+             {fun_t, Sys, [], [TypeOrFresh(Arg) || Arg <- Args], TypeOrFresh(Ret)})
           }
           || {letfun, AnnF, Entrypoint = {id, _, Name}, Args, _Type, [{guarded, _, [], Ret}]} <- Contents,
              Name =/= "init"
@@ -431,21 +469,30 @@ lookup_env1(#env{ namespace = Current, used_namespaces = UsedNamespaces, scopes
     %% Get the scope
     case maps:get(Qual, Scopes, false) of
         false -> false; %% TODO: return reason for not in scope
-        #scope{ funs = Funs, types = Types } ->
+        #scope{ funs = Funs, types = Types, consts = Consts, kind = ScopeKind } ->
             Defs = case Kind of
                      type -> Types;
                      term -> Funs
                    end,
             %% Look up the unqualified name
             case proplists:get_value(Name, Defs, false) of
-                false -> false;
+                false ->
+                    case proplists:get_value(Name, Consts, false) of
+                        false ->
+                            false;
+                        Const when AllowPrivate; ScopeKind == namespace ->
+                            {QName, Const};
+                        Const ->
+                            type_error({contract_treated_as_namespace_constant, Ann, QName}),
+                            {QName, Const}
+                    end;
                 {reserved_init, Ann1, Type} ->
                     type_error({cannot_call_init_function, Ann}),
                     {QName, {Ann1, Type}};  %% Return the type to avoid an extra not-in-scope error
                 {contract_fun, Ann1, Type} when AllowPrivate orelse QNameIsEvent ->
                     {QName, {Ann1, Type}};
                 {contract_fun, Ann1, Type} ->
-                    type_error({contract_treated_as_namespace, Ann, QName}),
+                    type_error({contract_treated_as_namespace_entrypoint, Ann, QName}),
                     {QName, {Ann1, Type}};
                 {Ann1, _} = E ->
                     %% Check that it's not private (or we can see private funs)
@@ -486,8 +533,11 @@ qname({qid,  _, Xs}) -> Xs;
 qname({con,  _, X})  -> [X];
 qname({qcon, _, Xs}) -> Xs.
 
--spec name(aeso_syntax:id() | aeso_syntax:con()) -> name().
-name({_, _, X}) -> X.
+-spec name(Named | {typed, _, Named, _}) -> name() when
+      Named :: aeso_syntax:id() | aeso_syntax:con().
+name({typed, _, X, _}) -> name(X);
+name({id, _, X}) -> X;
+name({con, _, X}) -> X.
 
 -spec qid(aeso_syntax:ann(), qname()) -> aeso_syntax:id() | aeso_syntax:qid().
 qid(Ann, [X]) -> {id, Ann, X};
@@ -1054,6 +1104,7 @@ infer_contract(Env0, What, Defs0, Options) ->
               ({fun_clauses, _, _, _, _}) -> function;
               ({fun_decl, _, _, _})       -> prototype;
               ({using, _, _, _, _})       -> using;
+              ({letval, _, _, _})         -> constant;
               (_)                         -> unexpected
            end,
     Get = fun(K, In) -> [ Def || Def <- In, Kind(Def) == K ] end,
@@ -1069,11 +1120,12 @@ infer_contract(Env0, What, Defs0, Options) ->
             contract_interface -> Env1;
             contract           -> bind_state(Env1)   %% bind state and put
         end,
-    {ProtoSigs, Decls} = lists:unzip([ check_fundecl(Env1, Decl) || Decl <- Get(prototype, Defs) ]),
+    {Env2C, Consts} = check_constants(Env2, Get(constant, Defs)),
+    {ProtoSigs, Decls} = lists:unzip([ check_fundecl(Env2C, Decl) || Decl <- Get(prototype, Defs) ]),
     [ type_error({missing_definition, Id}) || {fun_decl, _, Id, _} <- Decls,
                                               What =:= contract,
                                               get_option(no_code, false) =:= false ],
-    Env3      = bind_funs(ProtoSigs, Env2),
+    Env3      = bind_funs(ProtoSigs, Env2C),
     Functions = Get(function, Defs),
     %% Check for duplicates in Functions (we turn it into a map below)
     FunBind   = fun({letfun, Ann, {id, _, Fun}, _, _, _})   -> {Fun, {tuple_t, Ann, []}};
@@ -1093,7 +1145,7 @@ infer_contract(Env0, What, Defs0, Options) ->
     check_entrypoints(Defs1),
     destroy_and_report_type_errors(Env4),
     %% Add inferred types of definitions
-    {Env5, TypeDefs ++ Decls ++ Defs1}.
+    {Env5, TypeDefs ++ Decls ++ Consts ++ Defs1}.
 
 %% Restructure blocks into multi-clause fundefs (`fun_clauses`).
 -spec process_blocks([aeso_syntax:decl()]) -> [aeso_syntax:decl()].
@@ -1243,6 +1295,21 @@ opposite_variance(covariant) -> contravariant;
 opposite_variance(contravariant) -> covariant;
 opposite_variance(bivariant) -> bivariant.
 
+-spec check_constants(env(), [aeso_syntax:decl()]) -> {env(), [aeso_syntax:decl()]}.
+check_constants(Env = #env{ what = What }, Consts) ->
+    HasValidId = fun({letval, _, {id, _, _}, _})                -> true;
+                    ({letval, _, {typed, _, {id, _, _}, _}, _}) -> true;
+                    (_)                                         -> false
+                 end,
+    {Valid, Invalid} = lists:partition(HasValidId, Consts),
+    [ type_error({invalid_const_id, aeso_syntax:get_ann(Pat)}) || {letval, _, Pat, _} <- Invalid ],
+    [ type_error({illegal_const_in_interface, Ann}) || {letval, Ann, _, _} <- Valid, What == contract_interface ],
+    when_warning(warn_unused_constants, fun() -> potential_unused_constants(Env, Valid) end),
+    ConstMap = maps:from_list([ {name(Id), Const} || Const = {letval, _, Id, _} <- Valid ]),
+    DepGraph = maps:map(fun(_, Const) -> aeso_syntax_utils:used_ids(Const) end, ConstMap),
+    SCCs = aeso_utils:scc(DepGraph),
+    bind_consts(Env, ConstMap, SCCs, []).
+
 check_usings(Env, []) ->
     Env;
 check_usings(Env = #env{ used_namespaces = UsedNamespaces }, [{using, Ann, Con, Alias, Parts} | Rest]) ->
@@ -1514,7 +1581,7 @@ check_reserved_entrypoints(Funs) ->
 check_fundecl(Env, {fun_decl, Ann, Id = {id, _, Name}, Type = {fun_t, _, _, _, _}}) ->
     Type1 = {fun_t, _, Named, Args, Ret} = check_type(Env, Type),
     TypeSig = {type_sig, Ann, none, Named, Args, Ret},
-    register_implementation(Id, TypeSig),
+    register_implementation(Env, Id, TypeSig),
     {{Name, TypeSig}, {fun_decl, Ann, Id, Type1}};
 check_fundecl(Env, {fun_decl, Ann, Id = {id, _, Name}, Type}) ->
     type_error({fundecl_must_have_funtype, Ann, Id, Type}),
@@ -1522,13 +1589,16 @@ check_fundecl(Env, {fun_decl, Ann, Id = {id, _, Name}, Type}) ->
 
 %% Register the function FunId as implemented by deleting it from the functions
 %% to be implemented table if it is included there, or return true otherwise.
--spec register_implementation(FunId, FunSig) -> true | no_return() when
+-spec register_implementation(env(), FunId, FunSig) -> true | no_return() when
       FunId :: aeso_syntax:id(),
       FunSig :: typesig().
-register_implementation(Id, Sig) ->
+register_implementation(Env, Id, Sig) ->
     Name = name(Id),
     case ets_lookup(functions_to_implement, Name) of
-        [{Name, Interface, Decl = {fun_decl, _, DeclId, _}}] ->
+        [{Name, Interface, Decl = {fun_decl, _, DeclId, FunT}}] ->
+            When = {implement_interface_fun, aeso_syntax:get_ann(Sig), Name, name(Interface)},
+            unify(Env, typesig_to_fun_t(Sig), FunT, When),
+
             DeclStateful   = aeso_syntax:get_ann(stateful,   Decl, false),
             DeclPayable    = aeso_syntax:get_ann(payable,    Decl, false),
 
@@ -1556,7 +1626,7 @@ infer_nonrec(Env, LetFun) ->
     create_constraints(),
     NewLetFun = {{_, Sig}, _} = infer_letfun(Env, LetFun),
     check_special_funs(Env, NewLetFun),
-    register_implementation(get_letfun_id(LetFun), Sig),
+    register_implementation(Env, get_letfun_id(LetFun), Sig),
     solve_then_destroy_and_report_unsolved_constraints(Env),
     Result = {TypeSig, _} = instantiate(NewLetFun),
     print_typesig(TypeSig),
@@ -1586,11 +1656,11 @@ infer_letrec(Env, Defs) ->
     Inferred =
         [ begin
             Res    = {{Name, TypeSig}, LetFun} = infer_letfun(ExtendEnv, LF),
-            register_implementation(get_letfun_id(LetFun), TypeSig),
+            register_implementation(Env, get_letfun_id(LetFun), TypeSig),
             Got    = proplists:get_value(Name, Funs),
             Expect = typesig_to_fun_t(TypeSig),
             unify(Env, Got, Expect, {check_typesig, Name, Got, Expect}),
-            solve_constraints(Env),
+            solve_all_constraints(Env),
             ?PRINT_TYPES("Checked ~s : ~s\n",
                          [Name, pp(dereference_deep(Got))]),
             Res
@@ -1687,9 +1757,19 @@ lookup_name(Env = #env{ namespace = NS, current_function = CurFn }, As, Id, Opti
             type_error({unbound_variable, Id}),
             {Id, fresh_uvar(As)};
         {QId, {_, Ty}} ->
-            when_warning(warn_unused_variables, fun() -> used_variable(NS, name(CurFn), QId) end),
-            when_warning(warn_unused_functions,
-                         fun() -> register_function_call(NS ++ qname(CurFn), QId) end),
+            %% Variables and functions cannot be used when CurFn is `none`.
+            %% i.e. they cannot be used in toplevel constants
+            [ begin
+                when_warning(
+                    warn_unused_variables,
+                    fun() -> used_variable(NS, name(CurFn), QId) end),
+                when_warning(
+                    warn_unused_functions,
+                    fun() -> register_function_call(NS ++ qname(CurFn), QId) end)
+              end || CurFn =/= none ],
+
+            when_warning(warn_unused_constants, fun() -> used_constant(NS, QId) end),
+
             Freshen = proplists:get_value(freshen, Options, false),
             check_stateful(Env, Id, Ty),
             Ty1 = case Ty of
@@ -2054,6 +2134,81 @@ infer_expr(Env, Let = {letfun, Attrs, _, _, _, _}) ->
     type_error({missing_body_for_let, Attrs}),
     infer_expr(Env, {block, Attrs, [Let, abort_expr(Attrs, "missing body")]}).
 
+check_valid_const_expr({bool, _, _}) ->
+    true;
+check_valid_const_expr({int, _, _}) ->
+    true;
+check_valid_const_expr({char, _, _}) ->
+    true;
+check_valid_const_expr({string, _, _}) ->
+    true;
+check_valid_const_expr({bytes, _, _}) ->
+    true;
+check_valid_const_expr({account_pubkey, _, _}) ->
+    true;
+check_valid_const_expr({oracle_pubkey, _, _}) ->
+    true;
+check_valid_const_expr({oracle_query_id, _, _}) ->
+    true;
+check_valid_const_expr({contract_pubkey, _, _}) ->
+    true;
+check_valid_const_expr({id, _, "_"}) ->
+    true;
+check_valid_const_expr({Tag, _, _}) when Tag == id; Tag == qid; Tag == con; Tag == qcon ->
+    true;
+check_valid_const_expr({tuple, _, Cpts}) ->
+    lists:all(fun(X) -> X end, [ check_valid_const_expr(C) || C <- Cpts ]);
+check_valid_const_expr({list, _, Elems}) ->
+    lists:all(fun(X) -> X end, [ check_valid_const_expr(Elem) || Elem <- Elems ]);
+check_valid_const_expr({list_comp, _, _, _}) ->
+    false;
+check_valid_const_expr({typed, _, Body, _}) ->
+    check_valid_const_expr(Body);
+check_valid_const_expr({app, Ann, Fun, Args0}) ->
+    {_, Args} = split_args(Args0),
+    case aeso_syntax:get_ann(format, Ann) of
+        infix ->
+            lists:all(fun(X) -> X end, [ check_valid_const_expr(Arg) || Arg <- Args ]);
+        prefix ->
+            lists:all(fun(X) -> X end, [ check_valid_const_expr(Arg) || Arg <- Args ]);
+        _ ->
+            %% Applications of data constructors are allowed in constants
+            lists:member(element(1, Fun), [con, qcon])
+    end;
+check_valid_const_expr({'if', _, _, _, _}) ->
+    false;
+check_valid_const_expr({switch, _, _, _}) ->
+    false;
+check_valid_const_expr({record, _, Fields}) ->
+    lists:all(fun(X) -> X end, [ check_valid_const_expr(Expr) || {field, _, _, Expr} <- Fields ]);
+check_valid_const_expr({record, _, _, _}) ->
+    false;
+check_valid_const_expr({proj, _, Record, _}) ->
+    check_valid_const_expr(Record);
+% Maps
+check_valid_const_expr({map_get, _, _, _}) ->  %% map lookup
+    false;
+check_valid_const_expr({map_get, _, _, _, _}) ->  %% map lookup with default
+    false;
+check_valid_const_expr({map, _, KVs}) ->   %% map construction
+    lists:all(fun(X) -> X end, [ check_valid_const_expr(K) andalso check_valid_const_expr(V) || {K, V} <- KVs ]);
+check_valid_const_expr({map, _, _, _}) -> %% map update
+    false;
+check_valid_const_expr({block, _, _}) ->
+    false;
+check_valid_const_expr({record_or_map_error, _, Fields}) ->
+    lists:all(fun(X) -> X end, [ check_valid_const_expr(Expr) || {field, _, _, Expr} <- Fields ]);
+check_valid_const_expr({record_or_map_error, _, _, _}) ->
+    false;
+check_valid_const_expr({lam, _, _, _}) ->
+    false;
+check_valid_const_expr({letpat, _, _, _}) ->
+    false;
+check_valid_const_expr({letval, _, _, _}) ->
+    false;
+check_valid_const_expr({letfun, _, _, _, _, _}) ->
+    false.
+
 infer_var_args_fun(Env, {typed, Ann, Fun, FunType0}, NamedArgs, ArgTypes) ->
     FunType =
         case Fun of
@@ -2178,9 +2333,14 @@ infer_pattern(Env, Pattern) ->
     NewPattern = infer_expr(NewEnv, Pattern),
     {NewEnv#env{ in_pattern = Env#env.in_pattern }, NewPattern}.
 
-infer_case(Env = #env{ namespace = NS, current_function = {id, _, Fun} }, Attrs, Pattern, ExprType, GuardedBranches, SwitchType) ->
+infer_case(Env = #env{ namespace = NS, current_function = FunId }, Attrs, Pattern, ExprType, GuardedBranches, SwitchType) ->
     {NewEnv, NewPattern = {typed, _, _, PatType}} = infer_pattern(Env, Pattern),
-    when_warning(warn_unused_variables, fun() -> potential_unused_variables(NS, Fun, free_vars(Pattern)) end),
+
+    %% Make sure we are inside a function before warning about potentially unused var
+    [ when_warning(warn_unused_variables,
+                   fun() -> potential_unused_variables(NS, Fun, free_vars(Pattern)) end)
+      || {id, _, Fun} <- [FunId] ],
+
     InferGuardedBranches = fun({guarded, Ann, Guards, Branch}) ->
         NewGuards = lists:map(fun(Guard) ->
                                   check_expr(NewEnv#env{ in_guard = true }, Guard, {id, Attrs, "bool"})
@@ -2214,6 +2374,19 @@ infer_block(Env, Attrs, [E|Rest], BlockType) ->
     when_warning(warn_unused_return_value, fun() -> potential_unused_return_value(NewE) end),
     [NewE|infer_block(Env, Attrs, Rest, BlockType)].
 
+infer_const(Env, {letval, Ann, TypedId = {typed, _, Id = {id, _, _}, Type}, Expr}) ->
+    check_valid_const_expr(Expr) orelse type_error({invalid_const_expr, Id}),
+    NewExpr = check_expr(Env#env{ current_const = Id }, Expr, Type),
+    {letval, Ann, TypedId, NewExpr};
+infer_const(Env, {letval, Ann, Id = {id, AnnId, _}, Expr}) ->
+    check_valid_const_expr(Expr) orelse type_error({invalid_const_expr, Id}),
+    create_constraints(),
+    NewExpr = {typed, _, _, Type} = infer_expr(Env#env{ current_const = Id }, Expr),
+    solve_then_destroy_and_report_unsolved_constraints(Env),
+    IdType = setelement(2, Type, AnnId),
+    NewId = {typed, aeso_syntax:get_ann(Id), Id, IdType},
+    instantiate({letval, Ann, NewId, NewExpr}).
+
 infer_infix({BoolOp, As})
   when BoolOp =:= '&&'; BoolOp =:= '||' ->
     Bool = {id, As, "bool"},
@@ -2402,61 +2575,118 @@ get_constraints() ->
 destroy_constraints() ->
     ets_delete(constraints).
 
--spec solve_constraints(env()) -> ok.
-solve_constraints(Env) ->
-    %% First look for record fields that appear in only one type definition
-    IsAmbiguous =
-        fun(#field_constraint{
-               record_t = RecordType,
-               field    = Field={id, _Attrs, FieldName},
-               field_t  = FieldType,
-               kind     = Kind,
-               context  = When }) ->
-                Arity = fun_arity(dereference_deep(FieldType)),
-                FieldInfos = case Arity of
-                                 none -> lookup_record_field(Env, FieldName, Kind);
-                                 _    -> lookup_record_field_arity(Env, FieldName, Arity, Kind)
-                             end,
-                case FieldInfos of
-                    [] ->
-                        type_error({undefined_field, Field}),
-                        false;
-                    [#field_info{field_t = FldType, record_t = RecType}] ->
-                        create_freshen_tvars(),
-                        FreshFldType = freshen(FldType),
-                        FreshRecType = freshen(RecType),
-                        destroy_freshen_tvars(),
-                        unify(Env, FreshFldType, FieldType, {field_constraint, FreshFldType, FieldType, When}),
-                        unify(Env, FreshRecType, RecordType, {record_constraint, FreshRecType, RecordType, When}),
-                        false;
-                    _ ->
-                        %% ambiguity--need cleverer strategy
-                        true
-                end;
-           (_) -> true
-        end,
-    AmbiguousConstraints = lists:filter(IsAmbiguous, get_constraints()),
+%% Solve all constraints by iterating until no-progress
 
-    % The two passes on AmbiguousConstraints are needed
-    solve_ambiguous_constraints(Env, AmbiguousConstraints ++ AmbiguousConstraints).
+-spec solve_all_constraints(env()) -> ok.
+solve_all_constraints(Env) ->
+    Constraints = [C || C <- get_constraints(), not one_shot_field_constraint(Env, C) ],
+    solve_constraints_top(Env, Constraints).
 
--spec solve_ambiguous_constraints(env(), [constraint()]) -> ok.
-solve_ambiguous_constraints(Env, Constraints) ->
-    Unknown = solve_known_record_types(Env, Constraints),
-    if Unknown == [] -> ok;
-       length(Unknown) < length(Constraints) ->
-            %% progress! Keep trying.
-            solve_ambiguous_constraints(Env, Unknown);
+solve_constraints_top(Env, Constraints) ->
+    UnsolvedCs = solve_constraints(Env, Constraints),
+    Progress   = solve_unknown_record_constraints(Env, UnsolvedCs),
+
+    if length(UnsolvedCs) < length(Constraints) orelse Progress == true ->
+        solve_constraints_top(Env, UnsolvedCs);
        true ->
-            case solve_unknown_record_types(Env, Unknown) of
-                true -> %% Progress!
-                    solve_ambiguous_constraints(Env, Unknown);
-                _ -> ok %% No progress. Report errors later.
-            end
+        ok
     end.
 
+-spec solve_constraints(env(), [constraint()]) -> [constraint()].
+solve_constraints(Env, Constraints) ->
+    [ C1 || C <- Constraints, C1 <- [dereference_deep(C)], not solve_constraint(Env, C1) ].
+
+solve_unknown_record_constraints(Env, Constraints) ->
+    FieldCs      = lists:filter(fun(#field_constraint{record_t = {uvar, _, _}}) -> true; (_) -> false end, Constraints),
+    FieldCsUVars = lists:usort([UVar || #field_constraint{record_t = UVar = {uvar, _, _}} <- FieldCs]),
+
+    FieldConstraint = fun(#field_constraint{ field = F, kind = K, context = Ctx }) -> {K, Ctx, F} end,
+    FieldsForUVar = fun(UVar) ->
+                        [ FieldConstraint(FC) || FC = #field_constraint{record_t = U} <- FieldCs, U == UVar ]
+                    end,
+
+
+    Solutions = [ solve_for_uvar(Env, UVar, FieldsForUVar(UVar)) || UVar <- FieldCsUVars ],
+    case lists:member(true, Solutions) of
+        true  -> true;
+        false -> Solutions
+    end.
+
+%% -- Simple constraints --
+%% Returns true if solved (unified or type error)
+solve_constraint(_Env, #field_constraint{record_t = {uvar, _, _}}) ->
+    false;
+solve_constraint(Env, #field_constraint{record_t = RecordType,
+                                              field    = Field = {id, _As, FieldName},
+                                              field_t  = FieldType,
+                                              context  = When}) ->
+    RecId = record_type_name(RecordType),
+    Attrs = aeso_syntax:get_ann(RecId),
+    case lookup_type(Env, RecId) of
+        {_, {_Ann, {Formals, {What, Fields}}}} when What =:= record_t; What =:= contract_t ->
+            FieldTypes = [{Name, Type} || {field_t, _, {id, _, Name}, Type} <- Fields],
+            case proplists:get_value(FieldName, FieldTypes) of
+                undefined ->
+                    type_error({missing_field, Field, RecId});
+                FldType ->
+                    solve_field_constraint(Env, FieldType, FldType, RecordType, app_t(Attrs, RecId, Formals), When)
+            end;
+        _ ->
+            type_error({not_a_record_type, instantiate(RecordType), When})
+    end,
+    true;
+solve_constraint(Env, C = #dependent_type_constraint{}) ->
+    check_named_argument_constraint(Env, C);
+solve_constraint(Env, C = #named_argument_constraint{}) ->
+    check_named_argument_constraint(Env, C);
+solve_constraint(_Env, {is_bytes, _}) -> false;
+solve_constraint(Env, {add_bytes, Ann, _, A0, B0, C0}) ->
+    A = unfold_types_in_type(Env, dereference(A0)),
+    B = unfold_types_in_type(Env, dereference(B0)),
+    C = unfold_types_in_type(Env, dereference(C0)),
+    case {A, B, C} of
+        {{bytes_t, _, M}, {bytes_t, _, N}, _} -> unify(Env, {bytes_t, Ann, M + N}, C, {at, Ann});
+        {{bytes_t, _, M}, _, {bytes_t, _, R}} when R >= M -> unify(Env, {bytes_t, Ann, R - M}, B, {at, Ann});
+        {_, {bytes_t, _, N}, {bytes_t, _, R}} when R >= N -> unify(Env, {bytes_t, Ann, R - N}, A, {at, Ann});
+        _ -> false
+    end;
+solve_constraint(_, _) -> false.
+
+one_shot_field_constraint(Env, #field_constraint{record_t = RecordType,
+                                                 field    = Field = {id, _As, FieldName},
+                                                 field_t  = FieldType,
+                                                 kind     = Kind,
+                                                 context  = When}) ->
+    Arity = fun_arity(dereference_deep(FieldType)),
+    FieldInfos = case Arity of
+                     none -> lookup_record_field(Env, FieldName, Kind);
+                     _    -> lookup_record_field_arity(Env, FieldName, Arity, Kind)
+                 end,
+
+    case FieldInfos of
+        [] ->
+            type_error({undefined_field, Field}),
+            true;
+        [#field_info{field_t = FldType, record_t = RecType}] ->
+            solve_field_constraint(Env, FieldType, FldType, RecordType, RecType, When),
+            true;
+        _ ->
+            false
+    end;
+one_shot_field_constraint(_Env, _Constraint) ->
+    false.
+
+
+solve_field_constraint(Env, FieldType, FldType, RecordType, RecType, When) ->
+    create_freshen_tvars(),
+    FreshFldType = freshen(FldType),
+    FreshRecType = freshen(RecType),
+    destroy_freshen_tvars(),
+    unify(Env, FreshFldType, FieldType, {field_constraint, FreshFldType, FieldType, When}),
+    unify(Env, FreshRecType, RecordType, {record_constraint, FreshRecType, RecordType, When}).
+
 solve_then_destroy_and_report_unsolved_constraints(Env) ->
-    solve_constraints(Env),
+    solve_all_constraints(Env),
     destroy_and_report_unsolved_constraints(Env).
 
 destroy_and_report_unsolved_constraints(Env) ->
@@ -2487,21 +2717,10 @@ destroy_and_report_unsolved_constraints(Env) ->
                            (_)                   -> false
                         end, OtherCs5),
 
-    Unsolved = [ S || S <- [ solve_constraint(Env, dereference_deep(C)) || C <- NamedArgCs ],
-                      S == unsolved ],
-    [ type_error({unsolved_named_argument_constraint, C}) || C <- Unsolved ],
-
-    Unknown = solve_known_record_types(Env, FieldCs),
-    if Unknown == [] -> ok;
-       true ->
-            case solve_unknown_record_types(Env, Unknown) of
-                true   -> ok;
-                Errors -> [ type_error(Err) || Err <- Errors ]
-            end
-    end,
-
+    check_field_constraints(Env, FieldCs),
     check_record_create_constraints(Env, CreateCs),
     check_is_contract_constraints(Env, ContractCs),
+    check_named_args_constraints(Env, NamedArgCs),
     check_bytes_constraints(Env, BytesCs),
     check_aens_resolve_constraints(Env, AensResolveCs),
     check_oracle_type_constraints(Env, OracleTypeCs),
@@ -2519,20 +2738,21 @@ get_oracle_type(_Fun, _Args, _Ret) -> false.
 
 %% -- Named argument constraints --
 
-%% If false, a type error has been emitted, so it's safe to drop the constraint.
--spec check_named_argument_constraint(env(), named_argument_constraint()) -> true | false | unsolved.
+%% True if solved (unified or type error), false otherwise
+-spec check_named_argument_constraint(env(), named_argument_constraint()) -> true | false.
 check_named_argument_constraint(_Env, #named_argument_constraint{ args = {uvar, _, _} }) ->
-    unsolved;
+    false;
 check_named_argument_constraint(Env,
         C = #named_argument_constraint{ args = Args,
                                         name = Id = {id, _, Name},
                                         type = Type }) ->
     case [ T || {named_arg_t, _, {id, _, Name1}, T, _} <- Args, Name1 == Name ] of
         []  ->
-            type_error({bad_named_argument, Args, Id}),
-            false;
-        [T] -> unify(Env, T, Type, {check_named_arg_constraint, C}), true
-    end;
+            type_error({bad_named_argument, Args, Id});
+        [T] ->
+            unify(Env, T, Type, {check_named_arg_constraint, C})
+    end,
+    true;
 check_named_argument_constraint(Env,
         #dependent_type_constraint{ named_args_t = NamedArgsT0,
                                     named_args = NamedArgs,
@@ -2549,10 +2769,11 @@ check_named_argument_constraint(Env,
             ArgEnv = maps:from_list([ {Name, GetVal(Name, Default)}
                                       || {named_arg_t, _, {id, _, Name}, _, Default} <- NamedArgsT ]),
             GenType1 = specialize_dependent_type(ArgEnv, GenType),
-            unify(Env, GenType1, SpecType, {check_expr, App, GenType1, SpecType}),
-            true;
-        _ -> unify(Env, GenType, SpecType, {check_expr, App, GenType, SpecType}), true
-    end.
+            unify(Env, GenType1, SpecType, {check_expr, App, GenType1, SpecType});
+        _ ->
+            unify(Env, GenType, SpecType, {check_expr, App, GenType, SpecType})
+    end,
+    true.
 
 specialize_dependent_type(Env, Type) ->
     case dereference(Type) of
@@ -2568,53 +2789,16 @@ specialize_dependent_type(Env, Type) ->
         _ -> Type   %% Currently no deep dependent types
     end.
 
-%% -- Bytes constraints --
+check_field_constraints(Env, Constraints) ->
+    UnsolvedFieldCs = solve_constraints(Env, Constraints),
+    case solve_unknown_record_constraints(Env, UnsolvedFieldCs) of
+        true   -> ok;
+        Errors -> [ type_error(Err) || Err <- Errors ]
+    end.
 
-solve_constraint(_Env, #field_constraint{record_t = {uvar, _, _}}) ->
-    not_solved;
-solve_constraint(Env, C = #field_constraint{record_t = RecType,
-                                            field    = FieldName,
-                                            field_t  = FieldType,
-                                            context  = When}) ->
-    RecId = record_type_name(RecType),
-    Attrs = aeso_syntax:get_ann(RecId),
-    case lookup_type(Env, RecId) of
-        {_, {_Ann, {Formals, {What, Fields}}}} when What =:= record_t; What =:= contract_t ->
-            FieldTypes = [{Name, Type} || {field_t, _, {id, _, Name}, Type} <- Fields],
-            {id, _, FieldString} = FieldName,
-            case proplists:get_value(FieldString, FieldTypes) of
-                undefined ->
-                    type_error({missing_field, FieldName, RecId}),
-                    not_solved;
-                FldType ->
-                    create_freshen_tvars(),
-                    FreshFldType = freshen(FldType),
-                    FreshRecType = freshen(app_t(Attrs, RecId, Formals)),
-                    destroy_freshen_tvars(),
-                    unify(Env, FreshFldType, FieldType, {field_constraint, FreshFldType, FieldType, When}),
-                    unify(Env, FreshRecType, RecType, {record_constraint, FreshRecType, RecType, When}),
-                    C
-            end;
-        _ ->
-            type_error({not_a_record_type, instantiate(RecType), When}),
-            not_solved
-    end;
-solve_constraint(Env, C = #dependent_type_constraint{}) ->
-    check_named_argument_constraint(Env, C);
-solve_constraint(Env, C = #named_argument_constraint{}) ->
-    check_named_argument_constraint(Env, C);
-solve_constraint(_Env, {is_bytes, _}) -> ok;
-solve_constraint(Env, {add_bytes, Ann, _, A0, B0, C0}) ->
-    A = unfold_types_in_type(Env, dereference(A0)),
-    B = unfold_types_in_type(Env, dereference(B0)),
-    C = unfold_types_in_type(Env, dereference(C0)),
-    case {A, B, C} of
-        {{bytes_t, _, M}, {bytes_t, _, N}, _} -> unify(Env, {bytes_t, Ann, M + N}, C, {at, Ann});
-        {{bytes_t, _, M}, _, {bytes_t, _, R}} when R >= M -> unify(Env, {bytes_t, Ann, R - M}, B, {at, Ann});
-        {_, {bytes_t, _, N}, {bytes_t, _, R}} when R >= N -> unify(Env, {bytes_t, Ann, R - N}, A, {at, Ann});
-        _ -> ok
-    end;
-solve_constraint(_, _) -> ok.
+check_named_args_constraints(Env, Constraints) ->
+    UnsolvedNamedArgCs = solve_constraints(Env, Constraints),
+    [ type_error({unsolved_named_argument_constraint, C}) || C <- UnsolvedNamedArgCs ].
 
 check_bytes_constraints(Env, Constraints) ->
     InAddConstraint = [ T || {add_bytes, _, _, A, B, C} <- Constraints,
@@ -2711,30 +2895,6 @@ check_is_contract_constraints(Env, [C | Cs]) ->
     end,
     check_is_contract_constraints(Env, Cs).
 
--spec solve_unknown_record_types(env(), [field_constraint()]) -> true | [tuple()].
-solve_unknown_record_types(Env, Unknown) ->
-    UVars = lists:usort([UVar || #field_constraint{record_t = UVar = {uvar, _, _}} <- Unknown]),
-    Solutions = [solve_for_uvar(Env, UVar, [{Kind, When, Field}
-                                            || #field_constraint{record_t = U, field = Field, kind = Kind, context = When} <- Unknown,
-                                               U == UVar])
-                 || UVar <- UVars],
-    case lists:member(true, Solutions) of
-        true  -> true;
-        false -> Solutions
-    end.
-
-%% This will solve all kinds of constraints but will only return the
-%% unsolved field constraints
--spec solve_known_record_types(env(), [constraint()]) -> [field_constraint()].
-solve_known_record_types(Env, Constraints) ->
-    DerefConstraints = lists:map(fun(C = #field_constraint{record_t = RecordType}) ->
-                                        C#field_constraint{record_t = dereference(RecordType)};
-                                    (C) -> dereference_deep(C)
-                                 end, Constraints),
-    SolvedConstraints = lists:map(fun(C) -> solve_constraint(Env, dereference_deep(C)) end, DerefConstraints),
-    Unsolved = DerefConstraints--SolvedConstraints,
-    lists:filter(fun(#field_constraint{}) -> true; (_) -> false end, Unsolved).
-
 record_type_name({app_t, _Attrs, RecId, _Args}) when ?is_type_id(RecId) ->
     RecId;
 record_type_name(RecId) when ?is_type_id(RecId) ->
@@ -2913,16 +3073,12 @@ unify0(Env, A, B, Variance, When) ->
 unify1(_Env, {uvar, _, R}, {uvar, _, R}, _Variance, _When) ->
     true;
 unify1(_Env, {uvar, _, _}, {fun_t, _, _, var_args, _}, _Variance, When) ->
-    type_error({unify_varargs, When});
-unify1(Env, {uvar, A, R}, T, _Variance, When) ->
+    type_error({unify_varargs, When}),
+    false;
+unify1(_Env, {uvar, A, R}, T, _Variance, When) ->
     case occurs_check(R, T) of
         true ->
-            if
-                Env#env.unify_throws ->
-                    cannot_unify({uvar, A, R}, T, none, When);
-                true ->
-                    ok
-            end,
+            cannot_unify({uvar, A, R}, T, none, When),
             false;
         false ->
             ets_insert(type_vars, {R, T}),
@@ -2949,18 +3105,13 @@ unify1(Env, A = {con, _, NameA}, B = {con, _, NameB}, Variance, When) ->
     case is_subtype(Env, NameA, NameB, Variance) of
         true -> true;
         false ->
-            if
-                Env#env.unify_throws ->
-                    IsSubtype = is_subtype(Env, NameA, NameB, contravariant) orelse
-                                is_subtype(Env, NameA, NameB, covariant),
-                    Cxt = case IsSubtype of
-                              true  -> Variance;
-                              false -> none
-                          end,
-                    cannot_unify(A, B, Cxt, When);
-                true ->
-                    ok
-            end,
+            IsSubtype = is_subtype(Env, NameA, NameB, contravariant) orelse
+                        is_subtype(Env, NameA, NameB, covariant),
+            Cxt = case IsSubtype of
+                      true  -> Variance;
+                      false -> none
+                  end,
+            cannot_unify(A, B, Cxt, When),
             false
     end;
 unify1(_Env, {qid, _, Name}, {qid, _, Name}, _Variance, _When) ->
@@ -2974,9 +3125,11 @@ unify1(Env, {if_t, _, {id, _, Id}, Then1, Else1}, {if_t, _, {id, _, Id}, Then2,
     unify0(Env, Else1, Else2, Variance, When);
 
 unify1(_Env, {fun_t, _, _, _, _}, {fun_t, _, _, var_args, _}, _Variance, When) ->
-    type_error({unify_varargs, When});
+    type_error({unify_varargs, When}),
+    false;
 unify1(_Env, {fun_t, _, _, var_args, _}, {fun_t, _, _, _, _}, _Variance, When) ->
-    type_error({unify_varargs, When});
+    type_error({unify_varargs, When}),
+    false;
 unify1(Env, {fun_t, _, Named1, Args1, Result1}, {fun_t, _, Named2, Args2, Result2}, Variance, When)
   when length(Args1) == length(Args2) ->
     unify0(Env, Named1, Named2, opposite_variance(Variance), When) andalso
@@ -2998,7 +3151,7 @@ unify1(Env, {tuple_t, _, As}, {tuple_t, _, Bs}, Variance, When)
   when length(As) == length(Bs) ->
     unify0(Env, As, Bs, Variance, When);
 unify1(Env, {named_arg_t, _, Id1, Type1, _}, {named_arg_t, _, Id2, Type2, _}, Variance, When) ->
-    unify1(Env, Id1, Id2, Variance, {arg_name, Id1, Id2, When}),
+    unify1(Env, Id1, Id2, Variance, {arg_name, Id1, Id2, When}) andalso
     unify1(Env, Type1, Type2, Variance, When);
 %% The grammar is a bit inconsistent about whether types without
 %% arguments are represented as applications to an empty list of
@@ -3007,13 +3160,8 @@ unify1(Env, {app_t, _, T, []}, B, Variance, When) ->
     unify0(Env, T, B, Variance, When);
 unify1(Env, A, {app_t, _, T, []}, Variance, When) ->
     unify0(Env, A, T, Variance, When);
-unify1(Env, A, B, _Variance, When) ->
-    if
-        Env#env.unify_throws ->
-            cannot_unify(A, B, none, When);
-        true ->
-            ok
-    end,
+unify1(_Env, A, B, _Variance, When) ->
+    cannot_unify(A, B, none, When),
     false.
 
 is_subtype(_Env, NameA, NameB, invariant) ->
@@ -3177,6 +3325,7 @@ all_warnings() ->
     [ warn_unused_includes
     , warn_unused_stateful
     , warn_unused_variables
+    , warn_unused_constants
     , warn_unused_typedefs
     , warn_unused_return_value
     , warn_unused_functions
@@ -3254,6 +3403,17 @@ used_variable(Namespace, Fun, [VarName]) ->
     ets_match_delete(warnings, {unused_variable, '_', Namespace, Fun, VarName});
 used_variable(_, _, _) -> ok.
 
+%% Warnings (Unused constants)
+
+potential_unused_constants(#env{ what = namespace }, _Consts) ->
+    [];
+potential_unused_constants(#env{ namespace = Namespace }, Consts) ->
+    [ ets_insert(warnings, {unused_constant, Ann, Namespace, Name}) || {letval, _, {id, Ann, Name}, _} <- Consts ].
+
+used_constant(Namespace = [Contract], [Contract, ConstName]) ->
+    ets_match_delete(warnings, {unused_constant, '_', Namespace, ConstName});
+used_constant(_, _) -> ok.
+
 %% Warnings (Unused return value)
 
 potential_unused_return_value({typed, Ann, {app, _, {typed, _, _, {fun_t, _, _, _, {id, _, Type}}}, _}, _}) when Type /= "unit" ->
@@ -3299,9 +3459,11 @@ destroy_and_report_unused_functions() ->
 
 %% Warnings (Shadowing)
 
-warn_potential_shadowing(_, "_", _) -> ok;
-warn_potential_shadowing(Ann, Name, Vars) ->
-    case proplists:get_value(Name, Vars, false) of
+warn_potential_shadowing(_, _, "_") -> ok;
+warn_potential_shadowing(Env = #env{ vars = Vars }, Ann, Name) ->
+    CurrentScope = get_current_scope(Env),
+    Consts = CurrentScope#scope.consts,
+    case proplists:get_value(Name, Vars ++ Consts, false) of
         false -> ok;
         {AnnOld, _} -> ets_insert(warnings, {shadowing, Ann, Name, AnnOld})
     end.
@@ -3543,10 +3705,6 @@ mk_error({type_decl, _, {id, Pos, Name}, _}) ->
     Msg = io_lib:format("Empty type declarations are not supported. Type `~s` lacks a definition",
                         [Name]),
     mk_t_err(pos(Pos), Msg);
-mk_error({letval, _Pos, {id, Pos, Name}, _Def}) ->
-    Msg = io_lib:format("Toplevel \"let\" definitions are not supported. Value `~s` could be replaced by 0-argument function.",
-                        [Name]),
-    mk_t_err(pos(Pos), Msg);
 mk_error({stateful_not_allowed, Id, Fun}) ->
     Msg = io_lib:format("Cannot reference stateful function `~s` in the definition of non-stateful function `~s`.",
                         [pp(Id), pp(Fun)]),
@@ -3630,10 +3788,14 @@ mk_error({cannot_call_init_function, Ann}) ->
     Msg = "The 'init' function is called exclusively by the create contract transaction "
           "and cannot be called from the contract code.",
     mk_t_err(pos(Ann), Msg);
-mk_error({contract_treated_as_namespace, Ann, [Con, Fun] = QName}) ->
+mk_error({contract_treated_as_namespace_entrypoint, Ann, [Con, Fun] = QName}) ->
     Msg = io_lib:format("Invalid call to contract entrypoint `~s`.", [string:join(QName, ".")]),
     Cxt = io_lib:format("It must be called as `c.~s` for some `c : ~s`.", [Fun, Con]),
     mk_t_err(pos(Ann), Msg, Cxt);
+mk_error({contract_treated_as_namespace_constant, Ann, QName}) ->
+    Msg = io_lib:format("Invalid use of the contract constant `~s`.", [string:join(QName, ".")]),
+    Cxt = "Toplevel contract constants can only be used in the contracts where they are defined.",
+    mk_t_err(pos(Ann), Msg, Cxt);
 mk_error({bad_top_level_decl, Decl}) ->
     What = case element(1, Decl) of
                letval -> "function or entrypoint";
@@ -3794,6 +3956,23 @@ mk_error({unpreserved_payablity, Kind, ContractCon, InterfaceCon}) ->
     Msg = io_lib:format("Non-payable ~s `~s` cannot implement payable interface `~s`",
                         [KindStr, name(ContractCon), name(InterfaceCon)]),
     mk_t_err(pos(ContractCon), Msg);
+mk_error({mutually_recursive_constants, Consts}) ->
+    Msg = [ "Mutual recursion detected between the constants",
+            [ io_lib:format("\n  - `~s` at ~s", [name(Id), pp_loc(Ann)])
+                || {letval, Ann, Id, _} <- Consts ] ],
+    [{letval, Ann, _, _} | _] = Consts,
+    mk_t_err(pos(Ann), Msg);
+mk_error({invalid_const_id, Ann}) ->
+    Msg = "The name of the compile-time constant cannot have pattern matching",
+    mk_t_err(pos(Ann), Msg);
+mk_error({invalid_const_expr, ConstId}) ->
+    Msg = io_lib:format("Invalid expression in the definition of the constant `~s`", [name(ConstId)]),
+    Cxt = "You can only use the following expressions as constants: "
+          "literals, lists, tuples, maps, and other constants",
+    mk_t_err(pos(aeso_syntax:get_ann(ConstId)), Msg, Cxt);
+mk_error({illegal_const_in_interface, Ann}) ->
+    Msg = "Cannot define toplevel constants inside a contract interface",
+    mk_t_err(pos(Ann), Msg);
 mk_error(Err) ->
     Msg = io_lib:format("Unknown error: ~p", [Err]),
     mk_t_err(pos(0, 0), Msg).
@@ -3807,6 +3986,9 @@ mk_warning({unused_stateful, Ann, FunName}) ->
 mk_warning({unused_variable, Ann, _Namespace, _Fun, VarName}) ->
     Msg = io_lib:format("The variable `~s` is defined but never used.", [VarName]),
     aeso_warnings:new(pos(Ann), Msg);
+mk_warning({unused_constant, Ann, _Namespace, ConstName}) ->
+    Msg = io_lib:format("The constant `~s` is defined but never used.", [ConstName]),
+    aeso_warnings:new(pos(Ann), Msg);
 mk_warning({unused_typedef, Ann, QName, _Arity}) ->
     Msg = io_lib:format("The type `~s` is defined but never used.", [lists:last(QName)]),
     aeso_warnings:new(pos(Ann), Msg);
@@ -3912,8 +4094,8 @@ pp_when({if_branches, Then, ThenType0, Else, ElseType0}) ->
     Branches = [ {Then, ThenType} | [ {B, ElseType} || B <- if_branches(Else) ] ],
     {pos(element(1, hd(Branches))),
      io_lib:format("when comparing the types of the if-branches\n"
-                   "~s", [ [ io_lib:format("~s (at ~s)\n", [pp_typed("  - ", B, BType), pp_loc(B)])
-                           || {B, BType} <- Branches ] ])};
+                   "~s", [string:join([ io_lib:format("~s (at ~s)", [pp_typed("  - ", B, BType), pp_loc(B)])
+                                       || {B, BType} <- Branches ], "\n")])};
 pp_when({case_pat, Pat, PatType0, ExprType0}) ->
     {PatType, ExprType} = instantiate({PatType0, ExprType0}),
     {pos(Pat),
@@ -3960,6 +4142,10 @@ pp_when({var_args, Ann, Fun}) ->
     {pos(Ann)
     , io_lib:format("when resolving arguments of variadic function `~s`", [pp_expr(Fun)])
     };
+pp_when({implement_interface_fun, Ann, Entrypoint, Interface}) ->
+    { pos(Ann)
+    , io_lib:format("when implementing the entrypoint `~s` from the interface `~s`", [Entrypoint, Interface])
+    };
 pp_when(unknown) -> {pos(0,0), ""}.
 
 -spec pp_why_record(why_record()) -> {pos(), iolist()}.

src/aeso_compiler.erl

@@ -12,6 +12,8 @@
         , file/2
         , from_string/2
         , check_call/4
+        , decode_value/4
+        , encode_value/4
         , create_calldata/3
         , create_calldata/4
         , version/0
@@ -117,7 +119,7 @@ from_string1(ContractString, Options) ->
      , warnings := Warnings } = string_to_code(ContractString, Options),
     #{ child_con_env := ChildContracts } = FCodeEnv,
     SavedFreshNames = maps:get(saved_fresh_names, FCodeEnv, #{}),
-    {FateCode, VarsRegs} = aeso_fcode_to_fate:compile(ChildContracts, FCode, SavedFreshNames, Options),
+    FateCode = aeso_fcode_to_fate:compile(ChildContracts, FCode, SavedFreshNames, Options),
     pp_assembler(FateCode, Options),
     ByteCode = aeb_fate_code:serialize(FateCode, []),
     {ok, Version} = version(),
@@ -130,13 +132,7 @@ from_string1(ContractString, Options) ->
             payable => maps:get(payable, FCode),
             warnings => Warnings
            },
-    ResDbg = Res#{variables_registers => VarsRegs},
-    FinalRes =
-        case proplists:get_value(debug_info, Options, false) of
-            true  -> ResDbg;
-            false -> Res
-        end,
-    {ok, maybe_generate_aci(FinalRes, FoldedTypedAst, Options)}.
+    {ok, maybe_generate_aci(Res, FoldedTypedAst, Options)}.
 
 maybe_generate_aci(Result, FoldedTypedAst, Options) ->
     case proplists:get_value(aci, Options) of
@@ -188,30 +184,55 @@ check_call(Source, FunName, Args, Options) ->
     check_call1(Source, FunName, Args, Options).
 
 check_call1(ContractString0, FunName, Args, Options) ->
+    case add_extra_call(ContractString0, {call, FunName, Args}, Options) of
+        {ok, CallName, Code} ->
+            {def, _, _, FcodeArgs} = get_call_body(CallName, Code),
+            {ok, FunName, [ aeso_fcode_to_fate:term_to_fate(A) || A <- FcodeArgs ]};
+        Err = {error, _} ->
+            Err
+    end.
+
+add_extra_call(Contract0, Call, Options) ->
     try
         %% First check the contract without the __call function
         #{fcode := OrgFcode
         , fcode_env := #{child_con_env := ChildContracts}
-        , ast := Ast} = string_to_code(ContractString0, Options),
-        {FateCode, _} = aeso_fcode_to_fate:compile(ChildContracts, OrgFcode, #{}, []),
+        , ast := Ast} = string_to_code(Contract0, Options),
+        FateCode = aeso_fcode_to_fate:compile(ChildContracts, OrgFcode, #{}, []),
         %% collect all hashes and compute the first name without hash collision to
         SymbolHashes = maps:keys(aeb_fate_code:symbols(FateCode)),
         CallName = first_none_match(?CALL_NAME, SymbolHashes,
                                     lists:seq($1, $9) ++ lists:seq($A, $Z) ++ lists:seq($a, $z)),
-        ContractString = insert_call_function(Ast, ContractString0, CallName, FunName, Args),
-        #{fcode := Fcode} = string_to_code(ContractString, Options),
-        CallArgs = arguments_of_body(CallName, FunName, Fcode),
-
-        {ok, FunName, CallArgs}
+        Contract = insert_call_function(Ast, Contract0, CallName, Call),
+        {ok, CallName, string_to_code(Contract, Options)}
     catch
         throw:{error, Errors} -> {error, Errors}
     end.
 
-arguments_of_body(CallName, _FunName, Fcode) ->
+get_call_body(CallName, #{fcode := Fcode}) ->
     #{body := Body} = maps:get({entrypoint, list_to_binary(CallName)}, maps:get(functions, Fcode)),
-    {def, _FName, Args} = Body,
-    %% FName is either {entrypoint, list_to_binary(FunName)} or 'init'
-    [ aeso_fcode_to_fate:term_to_fate(A) || A <- Args ].
+    Body.
+
+encode_value(Contract0, Type, Value, Options) ->
+    case add_extra_call(Contract0, {value, Type, Value}, Options) of
+        {ok, CallName, Code} ->
+            Body = get_call_body(CallName, Code),
+            {ok, aeb_fate_encoding:serialize(aeso_fcode_to_fate:term_to_fate(Body))};
+        Err = {error, _} ->
+            Err
+    end.
+
+decode_value(Contract0, Type, FateValue, Options) ->
+    case add_extra_call(Contract0, {type, Type}, Options) of
+        {ok, CallName, Code} ->
+            #{ unfolded_typed_ast := TypedAst
+             , type_env           := TypeEnv} = Code,
+            {ok, _, Type0} = get_decode_type(CallName, TypedAst),
+            Type1 = aeso_ast_infer_types:unfold_types_in_type(TypeEnv, Type0, [unfold_record_types, unfold_variant_types]),
+            fate_data_to_sophia_value(Type0, Type1, FateValue);
+        Err = {error, _} ->
+            Err
+    end.
 
 first_none_match(_CallName, _Hashes, []) ->
     error(unable_to_find_unique_call_name);
@@ -224,14 +245,31 @@ first_none_match(CallName, Hashes, [Char|Chars]) ->
     end.
 
 %% Add the __call function to a contract.
--spec insert_call_function(aeso_syntax:ast(), string(), string(), string(), [string()]) -> string().
-insert_call_function(Ast, Code, Call, FunName, Args) ->
+-spec insert_call_function(aeso_syntax:ast(), string(), string(),
+                           {call, string(), [string()]} | {value, string(), string()} | {type, string()}) -> string().
+insert_call_function(Ast, Code, Call, {call, FunName, Args}) ->
     Ind = last_contract_indent(Ast),
     lists:flatten(
         [ Code,
           "\n\n",
           lists:duplicate(Ind, " "),
           "stateful entrypoint ", Call, "() = ", FunName, "(", string:join(Args, ","), ")\n"
+        ]);
+insert_call_function(Ast, Code, Call, {value, Type, Value}) ->
+    Ind = last_contract_indent(Ast),
+    lists:flatten(
+        [ Code,
+          "\n\n",
+          lists:duplicate(Ind, " "),
+          "entrypoint ", Call, "() : ", Type, " = ", Value, "\n"
+        ]);
+insert_call_function(Ast, Code, Call, {type, Type}) ->
+    Ind = last_contract_indent(Ast),
+    lists:flatten(
+        [ Code,
+          "\n\n",
+          lists:duplicate(Ind, " "),
+          "entrypoint ", Call, "(val : ", Type, ") = val\n"
         ]).
 
 -spec insert_init_function(string(), options()) -> string().
@@ -274,22 +312,25 @@ to_sophia_value(ContractString, FunName, ok, Data, Options0) ->
         {ok, _, Type0} = get_decode_type(FunName, TypedAst),
         Type   = aeso_ast_infer_types:unfold_types_in_type(TypeEnv, Type0, [unfold_record_types, unfold_variant_types]),
 
-        try
-            {ok, aeso_vm_decode:from_fate(Type, aeb_fate_encoding:deserialize(Data))}
-        catch throw:cannot_translate_to_sophia ->
-                Type1 = prettypr:format(aeso_pretty:type(Type0)),
-                Msg = io_lib:format("Cannot translate FATE value ~p\n  of Sophia type ~s",
-                                    [aeb_fate_encoding:deserialize(Data), Type1]),
-                {error, [aeso_errors:new(data_error, Msg)]};
-              _:_ ->
-                Type1 = prettypr:format(aeso_pretty:type(Type0)),
-                Msg = io_lib:format("Failed to decode binary as type ~s", [Type1]),
-                {error, [aeso_errors:new(data_error, Msg)]}
-        end
+        fate_data_to_sophia_value(Type0, Type, Data)
     catch
         throw:{error, Errors} -> {error, Errors}
     end.
 
+fate_data_to_sophia_value(Type, UnfoldedType, FateData) ->
+    try
+        {ok, aeso_vm_decode:from_fate(UnfoldedType, aeb_fate_encoding:deserialize(FateData))}
+    catch throw:cannot_translate_to_sophia ->
+            Type1 = prettypr:format(aeso_pretty:type(Type)),
+            Msg = io_lib:format("Cannot translate FATE value ~p\n  of Sophia type ~s",
+                                [aeb_fate_encoding:deserialize(FateData), Type1]),
+            {error, [aeso_errors:new(data_error, Msg)]};
+          _:_ ->
+            Type1 = prettypr:format(aeso_pretty:type(Type)),
+            Msg = io_lib:format("Failed to decode binary as type ~s", [Type1]),
+            {error, [aeso_errors:new(data_error, Msg)]}
+    end.
+
 -spec create_calldata(string(), string(), [string()]) ->
           {ok, binary()} | {error, [aeso_errors:error()]}.
 create_calldata(Code, Fun, Args) ->

src/aeso_fcode_to_fate.erl

@@ -52,7 +52,8 @@
                tailpos           = true,
                child_contracts   = #{},
                saved_fresh_names = #{},
-               options           = [] }).
+               options           = [],
+               debug_info        = false }).
 
 %% -- Debugging --------------------------------------------------------------
 
@@ -81,24 +82,16 @@ code_error(Err) ->
 compile(FCode, SavedFreshNames, Options) ->
     compile(#{}, FCode, SavedFreshNames, Options).
 compile(ChildContracts, FCode, SavedFreshNames, Options) ->
-    try
-        compile1(ChildContracts, FCode, SavedFreshNames, Options)
-    after
-        put(variables_registers, undefined)
-    end.
-
-compile1(ChildContracts, FCode, SavedFreshNames, Options) ->
     #{ contract_name := ContractName,
        functions     := Functions } = FCode,
     SFuns  = functions_to_scode(ChildContracts, ContractName, Functions, SavedFreshNames, Options),
     SFuns1 = optimize_scode(SFuns, Options),
     FateCode = to_basic_blocks(SFuns1),
     ?debug(compile, Options, "~s\n", [aeb_fate_asm:pp(FateCode)]),
-    FateCode1 = case proplists:get_value(include_child_contract_symbols, Options, false) of
-                    false -> FateCode;
-                    true -> add_child_symbols(ChildContracts, FateCode)
-                end,
-    {FateCode1, get_variables_registers()}.
+    case proplists:get_value(include_child_contract_symbols, Options, false) of
+        false -> FateCode;
+        true  -> add_child_symbols(ChildContracts, FateCode)
+    end.
 
 make_function_id(X) ->
     aeb_fate_code:symbol_identifier(make_function_name(X)).
@@ -123,31 +116,15 @@ functions_to_scode(ChildContracts, ContractName, Functions, SavedFreshNames, Opt
 
 function_to_scode(ChildContracts, ContractName, Functions, Name, Attrs0, Args, Body, ResType, SavedFreshNames, Options) ->
     {ArgTypes, ResType1} = typesig_to_scode(Args, ResType),
-    Attrs = Attrs0 -- [stateful], %% Only track private and payable from here.
+    Attrs = [ A || A <- Attrs0, A == private orelse A == payable ],
     Env = init_env(ChildContracts, ContractName, Functions, Name, Args, SavedFreshNames, Options),
-    [ add_variables_register(Env, Arg, Register) ||
-        proplists:get_value(debug_info, Options, false),
-        {Arg, Register} <- Env#env.vars ],
+    ArgsNames = [ X || {X, _} <- lists:reverse(Env#env.vars) ],
+
+    %% DBG_LOC is added before the function body to make it possible to break
+    %% at the function signature
     SCode = to_scode(Env, Body),
-    {Attrs, {ArgTypes, ResType1}, SCode}.
-
-get_variables_registers() ->
-    case get(variables_registers) of
-        undefined -> #{};
-        Vs        -> Vs
-    end.
-
-add_variables_register(Env = #env{saved_fresh_names = SavedFreshNames}, Name, Register) ->
-    Olds = get_variables_registers(),
-    RealName = maps:get(Name, SavedFreshNames, Name),
-    FunName =
-        case Env#env.current_function of
-            event -> "Chain.event";
-            {entrypoint, BinName} -> binary_to_list(BinName);
-            {local_fun, QualName} -> lists:last(QualName)
-        end,
-    New = {Env#env.contract, FunName, RealName},
-    put(variables_registers, Olds#{New => Register}).
+    DbgSCode = dbg_contract(Env) ++ dbg_loc(Env, Attrs0) ++ dbg_scoped_vars(Env, ArgsNames, SCode),
+    {Attrs, {ArgTypes, ResType1}, DbgSCode}.
 
 -define(tvars, '$tvars').
 
@@ -194,20 +171,20 @@ types_to_scode(Ts) -> lists:map(fun type_to_scode/1, Ts).
 %% -- Environment functions --
 
 init_env(ChildContracts, ContractName, FunNames, Name, Args, SavedFreshNames, Options) ->
-    #env{ vars      = [ {X, {arg, I}} || {I, {X, _}} <- with_ixs(Args) ],
-          contract  = ContractName,
-          child_contracts = ChildContracts,
-          locals    = FunNames,
-          current_function = Name,
-          options = Options,
-          tailpos   = true,
-          saved_fresh_names = SavedFreshNames }.
+    #env{ vars              = [ {X, {arg, I}} || {I, {X, _}} <- with_ixs(Args) ],
+          contract          = ContractName,
+          child_contracts   = ChildContracts,
+          locals            = FunNames,
+          current_function  = Name,
+          options           = Options,
+          tailpos           = true,
+          saved_fresh_names = SavedFreshNames,
+          debug_info        = proplists:get_value(debug_info, Options, false) }.
 
 next_var(#env{ vars = Vars }) ->
     1 + lists:max([-1 | [J || {_, {var, J}} <- Vars]]).
 
 bind_var(Name, Var, Env = #env{ vars = Vars }) ->
-    proplists:get_value(debug_info, Env#env.options, false) andalso add_variables_register(Env, Name, Var),
     Env#env{ vars = [{Name, Var} | Vars] }.
 
 bind_local(Name, Env) ->
@@ -234,7 +211,7 @@ serialize_contract_code(Env, C) ->
             Options = Env#env.options,
             SavedFreshNames = Env#env.saved_fresh_names,
             FCode = maps:get(C, Env#env.child_contracts),
-            {FateCode, _} = compile1(Env#env.child_contracts, FCode, SavedFreshNames, Options),
+            FateCode = compile(Env#env.child_contracts, FCode, SavedFreshNames, Options),
             ByteCode = aeb_fate_code:serialize(FateCode, []),
             {ok, Version} = aeso_compiler:version(),
             OriginalSourceCode = proplists:get_value(original_src, Options, ""),
@@ -268,44 +245,44 @@ lit_to_fate(Env, L) ->
 term_to_fate(E) -> term_to_fate(#env{}, #{}, E).
 term_to_fate(GlobEnv, E) -> term_to_fate(GlobEnv, #{}, E).
 
-term_to_fate(GlobEnv, _Env, {lit, L}) ->
+term_to_fate(GlobEnv, _Env, {lit, _, L}) ->
     lit_to_fate(GlobEnv, L);
 %% negative literals are parsed as 0 - N
-term_to_fate(_GlobEnv, _Env, {op, '-', [{lit, {int, 0}}, {lit, {int, N}}]}) ->
+term_to_fate(_GlobEnv, _Env, {op, _, '-', [{lit, _, {int, 0}}, {lit, _, {int, N}}]}) ->
     aeb_fate_data:make_integer(-N);
-term_to_fate(_GlobEnv, _Env, nil) ->
+term_to_fate(_GlobEnv, _Env, {nil, _}) ->
     aeb_fate_data:make_list([]);
-term_to_fate(GlobEnv, Env, {op, '::', [Hd, Tl]}) ->
+term_to_fate(GlobEnv, Env, {op, _, '::', [Hd, Tl]}) ->
     %% The Tl will translate into a list, because FATE lists are just lists
     [term_to_fate(GlobEnv, Env, Hd) | term_to_fate(GlobEnv, Env, Tl)];
-term_to_fate(GlobEnv, Env, {tuple, As}) ->
+term_to_fate(GlobEnv, Env, {tuple, _, As}) ->
     aeb_fate_data:make_tuple(list_to_tuple([ term_to_fate(GlobEnv, Env, A) || A<-As]));
-term_to_fate(GlobEnv, Env, {con, Ar, I, As}) ->
+term_to_fate(GlobEnv, Env, {con, _, Ar, I, As}) ->
     FateAs = [ term_to_fate(GlobEnv, Env, A) || A <- As ],
     aeb_fate_data:make_variant(Ar, I, list_to_tuple(FateAs));
-term_to_fate(_GlobEnv, _Env, {builtin, bits_all, []}) ->
+term_to_fate(_GlobEnv, _Env, {builtin, _, bits_all, []}) ->
     aeb_fate_data:make_bits(-1);
-term_to_fate(_GlobEnv, _Env, {builtin, bits_none, []}) ->
+term_to_fate(_GlobEnv, _Env, {builtin, _, bits_none, []}) ->
     aeb_fate_data:make_bits(0);
-term_to_fate(GlobEnv, _Env, {op, bits_set, [B, I]}) ->
+term_to_fate(GlobEnv, _Env, {op, _, bits_set, [B, I]}) ->
     {bits, N} = term_to_fate(GlobEnv, B),
     J         = term_to_fate(GlobEnv, I),
     {bits, N bor (1 bsl J)};
-term_to_fate(GlobEnv, _Env, {op, bits_clear, [B, I]}) ->
+term_to_fate(GlobEnv, _Env, {op, _, bits_clear, [B, I]}) ->
     {bits, N} = term_to_fate(GlobEnv, B),
     J         = term_to_fate(GlobEnv, I),
     {bits, N band bnot (1 bsl J)};
-term_to_fate(GlobEnv, Env, {'let', X, E, Body}) ->
+term_to_fate(GlobEnv, Env, {'let', _, X, E, Body}) ->
     Env1 = Env#{ X => term_to_fate(GlobEnv, Env, E) },
     term_to_fate(GlobEnv, Env1, Body);
-term_to_fate(_GlobEnv, Env, {var, X}) ->
+term_to_fate(_GlobEnv, Env, {var, _, X}) ->
     case maps:get(X, Env, undefined) of
         undefined -> throw(not_a_fate_value);
         V         -> V
     end;
-term_to_fate(_GlobEnv, _Env, {builtin, map_empty, []}) ->
+term_to_fate(_GlobEnv, _Env, {builtin, _, map_empty, []}) ->
     aeb_fate_data:make_map(#{});
-term_to_fate(GlobEnv, Env, {op, map_set, [M, K, V]}) ->
+term_to_fate(GlobEnv, Env, {op, _, map_set, [M, K, V]}) ->
     Map = term_to_fate(GlobEnv, Env, M),
     Map#{term_to_fate(GlobEnv, Env, K) => term_to_fate(GlobEnv, Env, V)};
 term_to_fate(_GlobEnv, _Env, _) ->
@@ -313,52 +290,59 @@ term_to_fate(_GlobEnv, _Env, _) ->
 
 to_scode(Env, T) ->
     try term_to_fate(Env, T) of
-        V -> [push(?i(V))]
+        V ->
+            FAnn = element(2, T),
+            [dbg_loc(Env, FAnn), push(?i(V))]
     catch throw:not_a_fate_value ->
         to_scode1(Env, T)
     end.
 
-to_scode1(Env, {lit, L}) ->
-    [push(?i(lit_to_fate(Env, L)))];
+to_scode1(Env, {lit, Ann, L}) ->
+    [ dbg_loc(Env, Ann), push(?i(lit_to_fate(Env, L))) ];
 
-to_scode1(_Env, nil) ->
-    [aeb_fate_ops:nil(?a)];
+to_scode1(Env, {nil, Ann}) ->
+    [ dbg_loc(Env, Ann), aeb_fate_ops:nil(?a) ];
 
-to_scode1(Env, {var, X}) ->
-    [push(lookup_var(Env, X))];
+to_scode1(Env, {var, Ann, X}) ->
+    [ dbg_loc(Env, Ann), push(lookup_var(Env, X)) ];
 
-to_scode1(Env, {con, Ar, I, As}) ->
+to_scode1(Env, {con, Ann, Ar, I, As}) ->
     N = length(As),
-    [[to_scode(notail(Env), A) || A <- As],
-     aeb_fate_ops:variant(?a, ?i(Ar), ?i(I), ?i(N))];
+    [ dbg_loc(Env, Ann),
+      [to_scode(notail(Env), A) || A <- As],
+      aeb_fate_ops:variant(?a, ?i(Ar), ?i(I), ?i(N)) ];
 
-to_scode1(Env, {tuple, As}) ->
+to_scode1(Env, {tuple, Ann, As}) ->
     N = length(As),
-    [[ to_scode(notail(Env), A) || A <- As ],
-     tuple(N)];
+    [ dbg_loc(Env, Ann),
+      [ to_scode(notail(Env), A) || A <- As ],
+      tuple(N) ];
 
-to_scode1(Env, {proj, E, I}) ->
-    [to_scode(notail(Env), E),
-     aeb_fate_ops:element_op(?a, ?i(I), ?a)];
+to_scode1(Env, {proj, Ann, E, I}) ->
+    [ dbg_loc(Env, Ann),
+      to_scode(notail(Env), E),
+      aeb_fate_ops:element_op(?a, ?i(I), ?a) ];
 
-to_scode1(Env, {set_proj, R, I, E}) ->
-    [to_scode(notail(Env), E),
-     to_scode(notail(Env), R),
-     aeb_fate_ops:setelement(?a, ?i(I), ?a, ?a)];
+to_scode1(Env, {set_proj, Ann, R, I, E}) ->
+    [ dbg_loc(Env, Ann),
+      to_scode(notail(Env), E),
+      to_scode(notail(Env), R),
+      aeb_fate_ops:setelement(?a, ?i(I), ?a, ?a) ];
 
-to_scode1(Env, {op, Op, Args}) ->
-    call_to_scode(Env, op_to_scode(Op), Args);
+to_scode1(Env, {op, Ann, Op, Args}) ->
+    [ dbg_loc(Env, Ann) | call_to_scode(Env, op_to_scode(Op), Args) ];
 
-to_scode1(Env, {'let', X, {var, Y}, Body}) ->
+to_scode1(Env, {'let', Ann, X, {var, _, Y}, Body}) ->
     Env1 = bind_var(X, lookup_var(Env, Y), Env),
-    to_scode(Env1, Body);
-to_scode1(Env, {'let', X, Expr, Body}) ->
+    [ dbg_loc(Env, Ann) | dbg_scoped_vars(Env1, [X], to_scode(Env1, Body)) ];
+to_scode1(Env, {'let', Ann, X, Expr, Body}) ->
     {I, Env1} = bind_local(X, Env),
-    [ to_scode(notail(Env), Expr),
-      aeb_fate_ops:store({var, I}, {stack, 0}),
-      to_scode(Env1, Body) ];
+    SCode = [ to_scode(notail(Env), Expr),
+              aeb_fate_ops:store({var, I}, {stack, 0}),
+              to_scode(Env1, Body) ],
+    [ dbg_loc(Env, Ann) | dbg_scoped_vars(Env1, [X], SCode) ];
 
-to_scode1(Env = #env{ current_function = Fun, tailpos = true }, {def, Fun, Args}) ->
+to_scode1(Env = #env{ current_function = Fun, tailpos = true, debug_info = false }, {def, Ann, Fun, Args}) ->
     %% Tail-call to current function, f(e0..en). Compile to
     %%      [ let xi = ei ]
     %%      [ STORE argi xi ]
@@ -371,61 +355,62 @@ to_scode1(Env = #env{ current_function = Fun, tailpos = true }, {def, Fun, Args}
                                 aeb_fate_ops:store({var, I}, ?a)],
                         {[I | Is], Acc1, Env2}
                     end, {[], [], Env}, Args),
-    [ Code,
+    [ dbg_loc(Env, Ann),
+      Code,
       [ aeb_fate_ops:store({arg, I}, {var, J})
         || {I, J} <- lists:zip(lists:seq(0, length(Vars) - 1),
                                lists:reverse(Vars)) ],
       loop ];
-to_scode1(Env, {def, Fun, Args}) ->
+to_scode1(Env, {def, Ann, Fun, Args}) ->
     FName = make_function_id(Fun),
     Lbl   = aeb_fate_data:make_string(FName),
-    call_to_scode(Env, local_call(Env, ?i(Lbl)), Args);
-to_scode1(Env, {funcall, Fun, Args}) ->
-    call_to_scode(Env, [to_scode(Env, Fun), local_call(Env, ?a)], Args);
+    [ dbg_loc(Env, Ann) | call_to_scode(Env, local_call(Env, ?i(Lbl)), Args) ];
+to_scode1(Env, {funcall, Ann, Fun, Args}) ->
+    [ dbg_loc(Env, Ann) | call_to_scode(Env, [to_scode(Env, Fun), local_call(Env, ?a)], Args) ];
 
-to_scode1(Env, {builtin, B, Args}) ->
-    builtin_to_scode(Env, B, Args);
+to_scode1(Env, {builtin, Ann, B, Args}) ->
+    [ dbg_loc(Env, Ann) | builtin_to_scode(Env, B, Args) ];
 
-to_scode1(Env, {remote, ArgsT, RetT, Ct, Fun, [Gas, Value, Protected | Args]}) ->
+to_scode1(Env, {remote, Ann, ArgsT, RetT, Ct, Fun, [Gas, Value, Protected | Args]}) ->
     Lbl = make_function_id(Fun),
     {ArgTypes, RetType0} = typesig_to_scode([{"_", T} || T <- ArgsT], RetT),
     ArgType = ?i(aeb_fate_data:make_typerep({tuple, ArgTypes})),
     RetType = ?i(aeb_fate_data:make_typerep(RetType0)),
-    case Protected of
-        {lit, {bool, false}} ->
+    SCode = case Protected of
+        {lit, _, {bool, false}} ->
             case Gas of
-                {builtin, call_gas_left, _} ->
+                {builtin, _, call_gas_left, _} ->
                     Call = aeb_fate_ops:call_r(?a, Lbl, ArgType, RetType, ?a),
                     call_to_scode(Env, Call, [Ct, Value | Args]);
                 _ ->
                     Call = aeb_fate_ops:call_gr(?a, Lbl, ArgType, RetType, ?a, ?a),
                     call_to_scode(Env, Call, [Ct, Value, Gas | Args])
             end;
-        {lit, {bool, true}} ->
+        {lit, _, {bool, true}} ->
             Call = aeb_fate_ops:call_pgr(?a, Lbl, ArgType, RetType, ?a, ?a, ?i(true)),
             call_to_scode(Env, Call, [Ct, Value, Gas | Args]);
         _ ->
             Call = aeb_fate_ops:call_pgr(?a, Lbl, ArgType, RetType, ?a, ?a, ?a),
             call_to_scode(Env, Call, [Ct, Value, Gas, Protected | Args])
-    end;
+    end,
+    [ dbg_loc(Env, Ann) | SCode ];
 
-to_scode1(_Env, {get_state, Reg}) ->
-    [push(?s(Reg))];
-to_scode1(Env, {set_state, Reg, Val}) ->
-    call_to_scode(Env, [{'STORE', ?s(Reg), ?a},
-                        tuple(0)], [Val]);
+to_scode1(Env, {get_state, Ann, Reg}) ->
+    [ dbg_loc(Env, Ann), push(?s(Reg)) ];
+to_scode1(Env, {set_state, Ann, Reg, Val}) ->
+    [ dbg_loc(Env, Ann) | call_to_scode(Env, [{'STORE', ?s(Reg), ?a}, tuple(0)], [Val]) ];
 
-to_scode1(Env, {closure, Fun, FVs}) ->
-    to_scode(Env, {tuple, [{lit, {string, make_function_id(Fun)}}, FVs]});
+to_scode1(Env, {closure, Ann, Fun, FVs}) ->
+    [ to_scode(Env, {tuple, Ann, [{lit, Ann, {string, make_function_id(Fun)}}, FVs]}) ];
 
-to_scode1(Env, {switch, Case}) ->
-    split_to_scode(Env, Case).
+to_scode1(Env, {switch, Ann, Case}) ->
+    [ dbg_loc(Env, Ann) | split_to_scode(Env, Case) ].
 
-local_call( Env, Fun) when Env#env.tailpos -> aeb_fate_ops:call_t(Fun);
-local_call(_Env, Fun)                      -> aeb_fate_ops:call(Fun).
+local_call( Env = #env{debug_info = false}, Fun) when Env#env.tailpos -> aeb_fate_ops:call_t(Fun);
+local_call(_Env, Fun)                                                 -> aeb_fate_ops:call(Fun).
 
-split_to_scode(Env, {nosplit, Expr}) ->
-    [switch_body, to_scode(Env, Expr)];
+split_to_scode(Env, {nosplit, Renames, Expr}) ->
+    [switch_body, dbg_scoped_vars(Env, Renames, to_scode(Env, Expr))];
 split_to_scode(Env, {split, {tuple, _}, X, Alts}) ->
     {Def, Alts1} = catchall_to_scode(Env, X, Alts),
     Arg = lookup_var(Env, X),
@@ -649,7 +634,7 @@ builtin_to_scode(Env, chain_bytecode_hash, [_Addr] = Args) ->
 builtin_to_scode(Env, chain_clone,
                  [InitArgsT, GasCap, Value, Prot, Contract | InitArgs]) ->
     case GasCap of
-        {builtin, call_gas_left, _} ->
+        {builtin, _, call_gas_left, _} ->
             call_to_scode(Env, aeb_fate_ops:clone(?a, ?a, ?a, ?a),
                           [Contract, InitArgsT, Value, Prot | InitArgs]
                          );
@@ -751,6 +736,77 @@ push(A) -> {'STORE', ?a, A}.
 tuple(0) -> push(?i({tuple, {}}));
 tuple(N) -> aeb_fate_ops:tuple(?a, N).
 
+%% -- Debug info functions --
+
+dbg_contract(#env{debug_info = false}) ->
+    [];
+dbg_contract(#env{contract = Contract}) ->
+    [{'DBG_CONTRACT', {immediate, Contract}}].
+
+dbg_loc(#env{debug_info = false}, _) ->
+    [];
+dbg_loc(_Env, Ann) ->
+    File = case proplists:get_value(file, Ann, no_file) of
+                no_file -> "";
+                F       -> F
+            end,
+    Line = proplists:get_value(line, Ann, undefined),
+    case Line of
+        undefined -> [];
+        _         -> [{'DBG_LOC', {immediate, File}, {immediate, Line}}]
+    end.
+
+dbg_scoped_vars(#env{debug_info = false}, _, SCode) ->
+    SCode;
+dbg_scoped_vars(_Env, [], SCode) ->
+    SCode;
+dbg_scoped_vars(Env, [{SavedVarName, Var} | Rest], SCode) ->
+    dbg_scoped_vars(Env, Rest, dbg_scoped_var(Env, SavedVarName, Var, SCode));
+dbg_scoped_vars(Env = #env{saved_fresh_names = SavedFreshNames}, [Var | Rest], SCode) ->
+    SavedVarName = maps:get(Var, SavedFreshNames, Var),
+    dbg_scoped_vars(Env, Rest, dbg_scoped_var(Env, SavedVarName, Var, SCode)).
+
+dbg_scoped_var(Env, SavedVarName, Var, SCode) ->
+    case SavedVarName == "_" orelse is_fresh_name(SavedVarName) of
+        true ->
+            SCode;
+        false ->
+            Register = lookup_var(Env, Var),
+            Def      = [{'DBG_DEF',   {immediate, SavedVarName}, Register}],
+            Undef    = [{'DBG_UNDEF', {immediate, SavedVarName}, Register}],
+            Def ++ dbg_undef(Undef, SCode)
+    end.
+
+is_fresh_name([$% | _]) ->
+    true;
+is_fresh_name(_) ->
+    false.
+
+dbg_undef(_Undef, missing) ->
+    missing;
+dbg_undef(Undef, loop) ->
+    [Undef, loop];
+dbg_undef(Undef, switch_body) ->
+    [switch_body, Undef];
+dbg_undef(Undef, {switch, Arg, Type, Alts, Catch}) ->
+    NewAlts   = [ dbg_undef(Undef, Alt) || Alt <- Alts ],
+    NewCatch  = dbg_undef(Undef, Catch),
+    NewSwitch = {switch, Arg, Type, NewAlts, NewCatch},
+    NewSwitch;
+dbg_undef(Undef, SCode) when is_list(SCode) ->
+    lists:droplast(SCode) ++ [dbg_undef(Undef, lists:last(SCode))];
+dbg_undef(Undef, SCode) when is_tuple(SCode); is_atom(SCode) ->
+    [Mnemonic | _] =
+        case is_tuple(SCode) of
+            true  -> tuple_to_list(SCode);
+            false -> [SCode]
+        end,
+    Op = aeb_fate_opcodes:m_to_op(Mnemonic),
+    case aeb_fate_opcodes:end_bb(Op) of
+        true  -> [Undef, SCode];
+        false -> [SCode, Undef]
+    end.
+
 %% -- Phase II ---------------------------------------------------------------
 %%  Optimize
 
@@ -886,6 +942,10 @@ attributes(I) ->
         loop                                  -> Impure(pc, []);
         switch_body                           -> Pure(none, []);
         'RETURN'                              -> Impure(pc, []);
+        {'DBG_LOC', _, _}                     -> Impure(none, []);
+        {'DBG_DEF', _, _}                     -> Impure(none, []);
+        {'DBG_UNDEF', _, _}                   -> Impure(none, []);
+        {'DBG_CONTRACT', _}                   -> Impure(none, []);
         {'RETURNR', A}                        -> Impure(pc, A);
         {'CALL', A}                           -> Impure(?a, [A]);
         {'CALL_R', A, _, B, C, D}             -> Impure(?a, [A, B, C, D]);
@@ -1081,11 +1141,16 @@ independent({i, _, I}, {i, _, J}) ->
     StackI = lists:member(?a, [WI | RI]),
     StackJ = lists:member(?a, [WJ | RJ]),
 
-    if  WI == pc; WJ == pc   -> false;     %% no jumps
-        not (PureI or PureJ) -> false;     %% at least one is pure
-        StackI and StackJ    -> false;     %% cannot both use the stack
-        WI == WJ             -> false;     %% cannot write to the same register
-        true                 ->
+    ReadStoreI = [] /= [ x || {store, _} <- RI ],
+    ReadStoreJ = [] /= [ x || {store, _} <- RJ ],
+
+    if  WI == pc; WJ == pc       -> false;  %% no jumps
+        not (PureI or PureJ)     -> false;  %% at least one is pure
+        StackI and StackJ        -> false;  %% cannot both use the stack
+        WI == WJ                 -> false;  %% cannot write to the same register
+        ReadStoreI and not PureJ -> false;  %% can't read store/state if other is impure
+        ReadStoreJ and not PureI -> false;  %% can't read store/state if other is impure
+        true                     ->
             %% and cannot write to each other's inputs
             not lists:member(WI, RJ) andalso
             not lists:member(WJ, RI)
@@ -1605,7 +1670,23 @@ bb(_Name, Code) ->
     Blocks  = lists:flatmap(fun split_calls/1, Blocks1),
     Labels  = maps:from_list([ {Ref, I} || {I, {Ref, _}} <- with_ixs(Blocks) ]),
     BBs     = [ set_labels(Labels, B) || B <- Blocks ],
-    maps:from_list(BBs).
+    maps:from_list(dbg_loc_filter(BBs)).
+
+%% Filter DBG_LOC instructions to keep one instruction per line
+dbg_loc_filter(BBs) ->
+    dbg_loc_filter(BBs, [], [], sets:new()).
+
+dbg_loc_filter([], _, AllBlocks, _) ->
+    lists:reverse(AllBlocks);
+dbg_loc_filter([{I, []} | Rest], AllOps, AllBlocks, DbgLocs) ->
+    dbg_loc_filter(Rest, [], [{I, lists:reverse(AllOps)} | AllBlocks], DbgLocs);
+dbg_loc_filter([{I, [Op = {'DBG_LOC', _, _} | Ops]} | Rest], AllOps, AllBlocks, DbgLocs) ->
+    case sets:is_element(Op, DbgLocs) of
+        true  -> dbg_loc_filter([{I, Ops} | Rest], AllOps, AllBlocks, DbgLocs);
+        false -> dbg_loc_filter([{I, Ops} | Rest], [Op | AllOps], AllBlocks, sets:add_element(Op, DbgLocs))
+    end;
+dbg_loc_filter([{I, [Op | Ops]} | Rest], AllOps, AllBlocks, DbgLocs) ->
+    dbg_loc_filter([{I, Ops} | Rest], [Op | AllOps], AllBlocks, DbgLocs).
 
 %% -- Break up scode into basic blocks --
 

src/aeso_syntax.erl

@@ -10,7 +10,7 @@
 
 -export([get_ann/1, get_ann/2, get_ann/3, set_ann/2, qualify/2]).
 
--export_type([ann_line/0, ann_col/0, ann_origin/0, ann_format/0, ann/0]).
+-export_type([ann_file/0, ann_line/0, ann_col/0, ann_origin/0, ann_format/0, ann/0]).
 -export_type([name/0, id/0, con/0, qid/0, qcon/0, tvar/0, op/0]).
 -export_type([bin_op/0, un_op/0]).
 -export_type([decl/0, letbind/0, typedef/0, pragma/0, fundecl/0]).
@@ -24,8 +24,9 @@
 -type ann_col()    :: integer().
 -type ann_origin() :: system | user.
 -type ann_format() :: '?:' | hex | infix | prefix | elif.
+-type ann_file()   :: string() | no_file.
 
--type ann() :: [ {line, ann_line()} | {col, ann_col()} | {format, ann_format()} | {origin, ann_origin()}
+-type ann() :: [ {file, ann_file()} | {line, ann_line()} | {col, ann_col()} | {format, ann_format()} | {origin, ann_origin()}
                | stateful | private | payable | main | interface | entrypoint].
 
 -type name() :: string().

src/aeso_syntax_utils.erl

@@ -31,11 +31,13 @@
             | aeso_syntax:field(aeso_syntax:expr())
             | aeso_syntax:stmt().
 fold(Alg = #alg{zero = Zero, plus = Plus, scoped = Scoped}, Fun, K, X) ->
+    ExprKind = if K == bind_expr -> bind_expr; true -> expr end,
+    TypeKind = if K == bind_type -> bind_type; true -> type end,
     Sum  = fun(Xs) -> lists:foldl(Plus, Zero, Xs) end,
     Same = fun(A) -> fold(Alg, Fun, K, A) end,
     Decl = fun(D) -> fold(Alg, Fun, decl, D) end,
-    Type = fun(T) -> fold(Alg, Fun, type, T) end,
-    Expr = fun(E) -> fold(Alg, Fun, expr, E) end,
+    Type = fun(T) -> fold(Alg, Fun, TypeKind, T) end,
+    Expr = fun(E) -> fold(Alg, Fun, ExprKind, E) end,
     BindExpr = fun(P) -> fold(Alg, Fun, bind_expr, P) end,
     BindType = fun(T) -> fold(Alg, Fun, bind_type, T) end,
     Top = Fun(K, X),
@@ -155,4 +157,3 @@ used(D) ->
                (_, _)             -> #{}
             end, decl, D)),
     lists:filter(NotBound, Xs).
-

src/aesophia.app.src

@@ -1,6 +1,6 @@
 {application, aesophia,
  [{description, "Compiler for Aeternity Sophia language"},
-  {vsn, "7.1.0"},
+  {vsn, "7.3.0"},
   {registered, []},
   {applications,
    [kernel,

test/aeso_compiler_tests.erl

@@ -222,6 +222,7 @@ compilable_contracts() ->
      "unapplied_contract_call",
      "unapplied_named_arg_builtin",
      "resolve_field_constraint_by_arity",
+     "toplevel_constants",
      "test" % Custom general-purpose test file. Keep it last on the list.
     ].
 
@@ -286,7 +287,11 @@ warnings() ->
       <<?PosW(48, 5)
         "Unused return value.">>,
       <<?PosW(60, 5)
-        "The function `dec` is defined but never used.">>
+        "The function `dec` is defined but never used.">>,
+      <<?PosW(73, 9)
+        "The definition of `const` shadows an older definition at line 70, column 3.">>,
+      <<?PosW(84, 7)
+        "The constant `c` is defined but never used.">>
      ]).
 
 failing_contracts() ->
@@ -658,10 +663,6 @@ failing_contracts() ->
          [<<?Pos(5, 28)
             "Invalid call to contract entrypoint `Foo.foo`.\n"
             "It must be called as `c.foo` for some `c : Foo`.">>])
-    , ?TYPE_ERROR(toplevel_let,
-                  [<<?Pos(2, 7)
-                     "Toplevel \"let\" definitions are not supported. "
-                     "Value `this_is_illegal` could be replaced by 0-argument function.">>])
     , ?TYPE_ERROR(empty_typedecl,
                   [<<?Pos(2, 8)
                      "Empty type declarations are not supported. "
@@ -859,17 +860,21 @@ failing_contracts() ->
                    <<?Pos(48, 5)
                      "Unused return value.">>,
                    <<?Pos(60, 5)
-                     "The function `dec` is defined but never used.">>
+                     "The function `dec` is defined but never used.">>,
+                   <<?Pos(73, 9)
+                     "The definition of `const` shadows an older definition at line 70, column 3.">>,
+                   <<?Pos(84, 7)
+                     "The constant `c` is defined but never used.">>
                   ])
     , ?TYPE_ERROR(polymorphism_contract_interface_recursive,
                   [<<?Pos(1,24)
                      "Trying to implement or extend an undefined interface `Z`">>
                   ])
     , ?TYPE_ERROR(polymorphism_contract_interface_same_name_different_type,
-                  [<<?Pos(9,5)
-                     "Duplicate definitions of `f` at\n"
-                     "  - line 8, column 5\n"
-                     "  - line 9, column 5">>])
+                  [<<?Pos(5,5)
+                     "Cannot unify `char` and `int`\n"
+                     "when implementing the entrypoint `f` from the interface `I1`">>
+                  ])
     , ?TYPE_ERROR(polymorphism_contract_missing_implementation,
                   [<<?Pos(4,20)
                      "Unimplemented entrypoint `f` from the interface `I1` in the contract `I2`">>
@@ -1193,6 +1198,74 @@ failing_contracts() ->
                    <<?Pos(13,20)
                      "Found a hole of type `'a`">>
                   ])
+    , ?TYPE_ERROR(toplevel_constants_contract_as_namespace,
+                  [<<?Pos(5,13)
+                     "Invalid use of the contract constant `G.const`.\n"
+                     "Toplevel contract constants can only be used in the contracts where they are defined.">>,
+                   <<?Pos(10,11)
+                     "Record type `G` does not have field `const`">>,
+                   <<?Pos(10,11)
+                     "Unbound field const">>,
+                   <<?Pos(11,11)
+                     "Record type `G` does not have field `const`">>,
+                   <<?Pos(11,11)
+                     "Unbound field const">>
+                  ])
+    , ?TYPE_ERROR(toplevel_constants_cycles,
+                  [<<?Pos(2,21)
+                     "Unbound variable `selfcycle`">>,
+                   <<?Pos(4,5)
+                     "Mutual recursion detected between the constants\n"
+                     "  - `cycle1` at line 4, column 5\n"
+                     "  - `cycle2` at line 5, column 5\n"
+                     "  - `cycle3` at line 6, column 5">>
+                  ])
+    , ?TYPE_ERROR(toplevel_constants_in_interface,
+                  [<<?Pos(2,10)
+                     "The name of the compile-time constant cannot have pattern matching">>,
+                   <<?Pos(3,5)
+                     "Cannot define toplevel constants inside a contract interface">>,
+                   <<?Pos(4,5)
+                     "Cannot define toplevel constants inside a contract interface">>
+                  ])
+    , ?TYPE_ERROR(toplevel_constants_invalid_expr,
+                  [<<?Pos(10,9)
+                     "Invalid expression in the definition of the constant `c01`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>,
+                   <<?Pos(11,9)
+                     "Invalid expression in the definition of the constant `c02`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>,
+                   <<?Pos(12,9)
+                     "Invalid expression in the definition of the constant `c03`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>,
+                   <<?Pos(13,9)
+                     "Invalid expression in the definition of the constant `c04`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>,
+                   <<?Pos(14,9)
+                     "Invalid expression in the definition of the constant `c05`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>,
+                   <<?Pos(17,9)
+                     "Invalid expression in the definition of the constant `c07`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>,
+                   <<?Pos(18,9)
+                     "Invalid expression in the definition of the constant `c08`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>,
+                   <<?Pos(19,9)
+                     "Invalid expression in the definition of the constant `c09`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>,
+                   <<?Pos(20,9)
+                     "Invalid expression in the definition of the constant `c10`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>,
+                   <<?Pos(21,9)
+                     "Invalid expression in the definition of the constant `c11`\n"
+                     "You can only use the following expressions as constants: literals, lists, tuples, maps, and other constants">>
+                  ])
+    , ?TYPE_ERROR(toplevel_constants_invalid_id,
+                  [<<?Pos(2,9)
+                     "The name of the compile-time constant cannot have pattern matching">>,
+                   <<?Pos(3,9)
+                     "The name of the compile-time constant cannot have pattern matching">>
+                  ])
     ].
 
 validation_test_() ->
@@ -1240,7 +1313,9 @@ validate(Contract1, Contract2) ->
                   true  -> [debug_mode];
                   false -> []
               end ++
-                  [{include, {file_system, [aeso_test_utils:contract_path()]}}]);
+                  [ {src_file, lists:concat([Contract2, ".aes"])}
+                  , {include, {file_system, [aeso_test_utils:contract_path()]}}
+                  ]);
         Error -> print_and_throw(Error)
     end.
 

test/contracts/all_syntax.aes

@@ -6,6 +6,7 @@
 namespace Ns =
   datatype d('a) = D | S(int) | M('a, list('a), int)
   private function fff() = 123
+  let const = 1
 
   stateful entrypoint
     f (1, x) = (_) => x
@@ -33,6 +34,8 @@ contract AllSyntax =
 
   type state = shakespeare(int)
 
+  let cc = "str"
+
   entrypoint init() = {
     johann = 1000,
     wolfgang = -10,

test/contracts/toplevel_constants.aes

@@ -0,0 +1,64 @@
+namespace N0 =
+    let nsconst = 1
+
+namespace N =
+    let nsconst = N0.nsconst
+
+contract C =
+    datatype event = EventX(int, string)
+
+    record account = { name    : string,
+                       balance : int }
+
+    let c01 = 2425
+    let c02 = -5
+    let c03 = ak_2gx9MEFxKvY9vMG5YnqnXWv1hCsX7rgnfvBLJS4aQurustR1rt
+    let c04 = true
+    let c05 = Bits.none
+    let c06 = #fedcba9876543210
+    let c07 = "str"
+    let c08 = [1, 2, 3]
+    let c09 = [(true, 24), (false, 19), (false, -42)]
+    let c10 = (42, "Foo", true)
+    let c11 = { name = "str", balance = 100000000 }
+    let c12 = {["foo"] = 19, ["bar"] = 42}
+    let c13 = Some(42)
+    let c14 = 11 : int
+    let c15 = EventX(0, "Hello")
+    let c16 = #000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f
+    let c17 = #000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f
+    let c18 = RelativeTTL(50)
+    let c19 = ok_2YNyxd6TRJPNrTcEDCe9ra59SVUdp9FR9qWC5msKZWYD9bP9z5
+    let c20 = oq_2oRvyowJuJnEkxy58Ckkw77XfWJrmRgmGaLzhdqb67SKEL1gPY
+    let c21 = ct_Ez6MyeTMm17YnTnDdHTSrzMEBKmy7Uz2sXu347bTDPgVH2ifJ : C
+    let c22 = N.nsconst
+    let c23 = c01
+    let c24 = c11.name
+    let c25 : int = 1
+
+    entrypoint f01() = c01
+    entrypoint f02() = c02
+    entrypoint f03() = c03
+    entrypoint f04() = c04
+    entrypoint f05() = c05
+    entrypoint f06() = c06
+    entrypoint f07() = c07
+    entrypoint f08() = c08
+    entrypoint f09() = c09
+    entrypoint f10() = c10
+    entrypoint f11() = c11
+    entrypoint f12() = c12
+    entrypoint f13() = c13
+    entrypoint f14() = c14
+    entrypoint f15() = c15
+    entrypoint f16() = c16
+    entrypoint f17() = c17
+    entrypoint f18() = c18
+    entrypoint f19() = c19
+    entrypoint f20() = c20
+    entrypoint f21() = c21
+    entrypoint f22() = c22
+    entrypoint f23() = c23
+    entrypoint f24() = c24
+    entrypoint f25() = c25
+    entrypoint fqual() = C.c01

test/contracts/toplevel_constants_contract_as_namespace.aes

@@ -0,0 +1,11 @@
+contract G =
+    let const = 1
+
+main contract C =
+    let c = G.const
+
+    stateful entrypoint f() =
+        let g = Chain.create() : G
+
+        g.const
+        g.const()

test/contracts/toplevel_constants_cycles.aes

@@ -0,0 +1,6 @@
+contract C =
+    let selfcycle = selfcycle
+
+    let cycle1 = cycle2
+    let cycle2 = cycle3
+    let cycle3 = cycle1

test/contracts/toplevel_constants_in_interface.aes

@@ -0,0 +1,7 @@
+contract interface I =
+    let (x::y::_) = [1,2,3]
+    let c = 10
+    let d = 10
+
+contract C =
+    entrypoint init() = ()

test/contracts/toplevel_constants_invalid_expr.aes

@@ -0,0 +1,21 @@
+main contract C =
+    record account = { name    : string,
+                       balance : int }
+
+    let one = 1
+    let opt = Some(5)
+    let acc = { name = "str", balance = 100000 }
+    let mpp = {["foo"] = 19, ["bar"] = 42}
+
+    let c01 = [x | x <- [1,2,3,4,5]]
+    let c02 = [x + k | x <- [1,2,3,4,5], let k = x*x]
+    let c03 = [x + y | x <- [1,2,3,4,5], let k = x*x, if (k > 5), y <- [k, k+1, k+2]]
+    let c04 = if (one > 2) 3 else 4
+    let c05 = switch (opt)
+                 Some(x) => x
+                 None => 2
+    let c07 = acc{ balance = one }
+    let c08 = mpp["foo"]
+    let c09 = mpp["non" = 10]
+    let c10 = mpp{["foo"] = 20}
+    let c11 = (x) => x + 1

test/contracts/toplevel_constants_invalid_id.aes

@@ -0,0 +1,3 @@
+contract C =
+    let x::_ = [1,2,3,4]
+    let y::(p = z::_) = [1,2,3,4]

test/contracts/toplevel_let.aes

@@ -1,3 +0,0 @@
-contract C =
-  let this_is_illegal = 2/0
-  entrypoint this_is_legal() = 2/0

test/contracts/warnings.aes

@@ -65,3 +65,24 @@ contract Remote =
 contract C = 
   payable stateful entrypoint
     call_missing_con() : int = (ct_1111111111111111111111111111112JF6Dz72 : Remote).id(value = 1, 0)
+
+namespace ShadowingConst =
+  let const = 1
+
+  function f() =
+    let const = 2
+    const
+
+namespace UnusedConstNamespace =
+  // No warnings should be shown even though const is not used
+  let const = 1
+
+contract UnusedConstContract =
+  // Only `c` should show a warning because it is never used in the contract
+  let a = 1
+  let b = 2
+  let c = 3
+
+  entrypoint f() =
+    // Both normal access and qualified access should prevent the unused const warning
+    a + UnusedConstContract.b