Fix error messages for some illegal constructions, fix absolute path includes (#251)

* Updated tests, banned type decls and toplevel letvals

* Properly ban nested contracts

* Fix including by path

* Fix error message test

* Fix prettpr attr display. Make dialyzer happy

* More tests

* Fixed type printing

* Updated docs

docs/sophia.md

@@ -446,6 +446,13 @@ Example syntax:
 // yields [12,13,14,20,21,22,30,31,32]
 ```
 
+Lists can be constructed using the range syntax using special `..` operator:
+```
+[1..4] == [1,2,3,4] 
+```
+The ranges are always ascending and have step equal to 1.
+
+
 Please refer to the [standard library](sophia_stdlib.md#List) for the predefined functionalities.
 
 ### Maps and records
@@ -825,15 +832,17 @@ In describing the syntax below, we use the following conventions:
 A Sophia file consists of a sequence of *declarations* in a layout block.
 
 ```c
-File ::= Block(Decl)
+File ::= Block(TopDecl)
-Decl ::= ['payable'] 'contract' Con '=' Block(Decl)
+
+TopDecl ::= ['payable'] 'contract' Con '=' Block(Decl)
        | 'namespace' Con '=' Block(Decl)
        | '@compiler' PragmaOp Version
        | 'include' String
-       | 'type'     Id ['(' TVar* ')'] ['=' TypeAlias]
+
+Decl ::= 'type'     Id ['(' TVar* ')'] '=' TypeAlias
        | 'record'   Id ['(' TVar* ')'] '=' RecordType
        | 'datatype' Id ['(' TVar* ')'] '=' DataType
-       | EModifier* ('entrypoint' | 'function') Block(FunDecl)
+       | (EModifier* 'entrypoint' | FModifier* 'function') Block(FunDecl)
 
 FunDecl ::= Id ':' Type                             // Type signature
           | Id Args [':' Type] '=' Block(Stmt)      // Definition
@@ -945,6 +954,7 @@ Expr ::= '(' LamArgs ')' '=>' Block(Stmt)   // Anonymous function    (x) => x +
        | '[' Sep(Expr, ',') ']'             // List                  [1, 2, 3]
        | '[' Expr '|' Sep(Generator, ',') ']'
                                             // List comprehension    [k | x <- [1], if (f(x)), let k = x+1]
+       | '[' Expr '..' Expr ']'             // List range            [1..n]
        | '{' Sep(FieldUpdate, ',') '}'      // Record or map value   {x = 0, y = 1}, {[key] = val}
        | '(' Expr ')'                       // Parens                (1 + 2) * 3
        | Id | Con | QId | QCon              // Identifiers           x, None, Map.member, AELib.Token

src/aeso_ast_infer_types.erl

@@ -2262,6 +2262,24 @@ mk_t_err(Pos, Msg) ->
 mk_t_err(Pos, Msg, Ctxt) ->
     aeso_errors:new(type_error, Pos, lists:flatten(Msg), lists:flatten(Ctxt)).
 
+mk_error({higher_kinded_typevar, T}) ->
+    Msg = io_lib:format("Type ~s is a higher kinded type variable\n"
+                        "(takes another type as an argument)\n", [pp(instantiate(T))]
+                       ),
+    mk_t_err(pos(T), Msg);
+mk_error({wrong_type_arguments, X, ArityGiven, ArityReal}) ->
+    Msg = io_lib:format("Arity for ~s doesn't match. Expected ~p, got ~p\n"
+                       , [pp(instantiate(X)), ArityReal, ArityGiven]
+                       ),
+    mk_t_err(pos(X), Msg);
+mk_error({unnamed_map_update_with_default, Upd}) ->
+    Msg = "Invalid map update with default\n",
+    mk_t_err(pos(Upd), Msg);
+mk_error({fundecl_must_have_funtype, _Ann, Id, Type}) ->
+    Msg = io_lib:format("~s at ~s was declared with an invalid type ~s.\n"
+                       "Entrypoints and functions must have functional types"
+                       , [pp(Id), pp_loc(Id), pp(instantiate(Type))]),
+    mk_t_err(pos(Id), Msg);
 mk_error({cannot_unify, A, B, When}) ->
     Msg = io_lib:format("Cannot unify ~s\n         and ~s\n",
                         [pp(instantiate(A)), pp(instantiate(B))]),
@@ -2344,14 +2362,6 @@ mk_error({indexed_type_must_be_word, Type, Type1}) ->
     Msg = io_lib:format("The indexed type ~s (at ~s) equals ~s which is not a word type\n",
                         [pp_type("", Type), pp_loc(Type), pp_type("", Type1)]),
     mk_t_err(pos(Type), Msg);
-mk_error({payload_type_must_be_string, Type, Type}) ->
-    Msg = io_lib:format("The payload type ~s (at ~s) should be string\n",
-                        [pp_type("", Type), pp_loc(Type)]),
-    mk_t_err(pos(Type), Msg);
-mk_error({payload_type_must_be_string, Type, Type1}) ->
-    Msg = io_lib:format("The payload type ~s (at ~s) equals ~s but it should be string\n",
-                        [pp_type("", Type), pp_loc(Type), pp_type("", Type1)]),
-    mk_t_err(pos(Type), Msg);
 mk_error({event_0_to_3_indexed_values, Constr}) ->
     Msg = io_lib:format("The event constructor ~s (at ~s) has too many indexed values (max 3)\n",
                         [name(Constr), pp_loc(Constr)]),
@@ -2395,13 +2405,21 @@ mk_error({include, _, {string, Pos, Name}}) ->
                         [binary_to_list(Name), pp_loc(Pos)]),
     mk_t_err(pos(Pos), Msg);
 mk_error({namespace, _Pos, {con, Pos, Name}, _Def}) ->
-    Msg = io_lib:format("Nested namespace not allowed\nNamespace '~s' at ~s not defined at top level.\n",
+    Msg = io_lib:format("Nested namespaces are not allowed\nNamespace '~s' at ~s not defined at top level.\n",
+                        [Name, pp_loc(Pos)]),
+    mk_t_err(pos(Pos), Msg);
+mk_error({contract, _Pos, {con, Pos, Name}, _Def}) ->
+    Msg = io_lib:format("Nested contracts are not allowed\nContract '~s' at ~s not defined at top level.\n",
+                        [Name, pp_loc(Pos)]),
+    mk_t_err(pos(Pos), Msg);
+mk_error({type_decl, _, {id, Pos, Name}, _}) ->
+    Msg = io_lib:format("Empty type declarations are not supported\nType ~s at ~s lacks a definition\n",
+                        [Name, pp_loc(Pos)]),
+    mk_t_err(pos(Pos), Msg);
+mk_error({letval, _Pos, {id, Pos, Name}, _Def}) ->
+    Msg = io_lib:format("Toplevel \"let\" definitions are not supported\nValue ~s at ~s could be replaced by 0-argument function\n",
                         [Name, pp_loc(Pos)]),
     mk_t_err(pos(Pos), Msg);
-mk_error({repeated_arg, Fun, Arg}) ->
-    Msg = io_lib:format("Repeated argument ~s to function ~s (at ~s).\n",
-                        [Arg, pp(Fun), pp_loc(Fun)]),
-    mk_t_err(pos(Fun), Msg);
 mk_error({stateful_not_allowed, Id, Fun}) ->
     Msg = io_lib:format("Cannot reference stateful function ~s (at ~s)\nin the definition of non-stateful function ~s.\n",
                         [pp(Id), pp_loc(Id), pp(Fun)]),

src/aeso_ast_to_fcode.erl

@@ -291,7 +291,6 @@ decls_to_fcode(Env, Decls) ->
                 end, Env1, Decls).
 
 -spec decl_to_fcode(env(), aeso_syntax:decl()) -> env().
-decl_to_fcode(Env, {type_decl, _, _, _}) -> Env;
 decl_to_fcode(Env = #{context := {main_contract, _}}, {fun_decl, _, Id, _}) ->
     case is_no_code(Env) of
         false -> fcode_error({missing_definition, Id});

src/aeso_compiler.erl

@@ -336,12 +336,12 @@ to_sophia_value(ContractString, FunName, ok, Data, Options0) ->
                 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(Type)),
+                        Type1 = prettypr:format(aeso_pretty:type(Type0)),
                         Msg = io_lib:format("Cannot translate FATE value ~p\n  of Sophia type ~s\n",
                                             [aeb_fate_encoding:deserialize(Data), Type1]),
                         {error, [aeso_errors:new(data_error, Msg)]};
                       _:_ ->
-                        Type1 = prettypr:format(aeso_pretty:type(Type)),
+                        Type1 = prettypr:format(aeso_pretty:type(Type0)),
                         Msg = io_lib:format("Failed to decode binary as type ~s\n", [Type1]),
                         {error, [aeso_errors:new(data_error, Msg)]}
                end

src/aeso_parser.erl

@@ -656,8 +656,14 @@ stdlib_options() ->
 
 get_include_code(File, Ann, Opts) ->
     case {read_file(File, Opts), read_file(File, stdlib_options())} of
-        {{ok, _}, {ok,_ }} ->
+        {{ok, Bin}, {ok, _}} ->
-            fail(ann_pos(Ann), "Illegal redefinition of standard library " ++ File);
+            case filename:basename(File) == File of
+                true -> { error
+                        , fail( ann_pos(Ann)
+                              , "Illegal redefinition of standard library " ++ binary_to_list(File))};
+                %% If a path is provided then the stdlib takes lower priority
+                false -> {ok, binary_to_list(Bin)}
+            end;
         {_, {ok, Bin}} ->
             {ok, binary_to_list(Bin)};
         {{ok, Bin}, _} ->

src/aeso_pretty.erl

@@ -145,8 +145,12 @@ decl(D, Options) ->
     with_options(Options, fun() -> decl(D) end).
 
 -spec decl(aeso_syntax:decl()) -> doc().
-decl({contract, _, C, Ds}) ->
+decl({contract, Attrs, C, Ds}) ->
-    block(follow(text("contract"), hsep(name(C), text("="))), decls(Ds));
+    Mod = fun({Mod, true}) when Mod == payable ->
+                  text(atom_to_list(Mod));
+             (_) -> empty() end,
+    block(follow( hsep(lists:map(Mod, Attrs) ++ [text("contract")])
+                , hsep(name(C), text("="))), decls(Ds));
 decl({namespace, _, C, Ds}) ->
     block(follow(text("namespace"), hsep(name(C), text("="))), decls(Ds));
 decl({pragma, _, Pragma}) -> pragma(Pragma);
@@ -155,13 +159,16 @@ decl({type_def, _, T, Vars, Def}) ->
     Kind = element(1, Def),
     equals(typedecl(Kind, T, Vars), typedef(Def));
 decl({fun_decl, Ann, F, T}) ->
+    Mod = fun({Mod, true}) when Mod == private; Mod == stateful; Mod == payable ->
+                  text(atom_to_list(Mod));
+             (_) -> empty() end,
     Fun = case aeso_syntax:get_ann(entrypoint, Ann, false) of
             true  -> text("entrypoint");
             false -> text("function")
           end,
-    hsep(Fun, typed(name(F), T));
+    hsep(lists:map(Mod, Ann) ++ [Fun, typed(name(F), T)]);
 decl(D = {letfun, Attrs, _, _, _, _}) ->
-    Mod = fun({Mod, true}) when Mod == private; Mod == stateful ->
+    Mod = fun({Mod, true}) when Mod == private; Mod == stateful; Mod == payable ->
                             text(atom_to_list(Mod));
              (_) -> empty() end,
     Fun = case aeso_syntax:get_ann(entrypoint, Attrs, false) of
@@ -364,7 +371,8 @@ expr_p(_, {Type, _, Bin})
          Type == oracle_query_id ->
     text(binary_to_list(aeser_api_encoder:encode(Type, Bin)));
 expr_p(_, {string, _, <<>>}) -> text("\"\"");
-expr_p(_, {string, _, S}) -> term(binary_to_list(S));
+expr_p(_, {string, _, S}) ->
+    text(io_lib:format("\"~s\"", [binary_to_list(S)]));
 expr_p(_, {char, _, C}) ->
     case C of
         $' -> text("'\\''");
@@ -486,6 +494,3 @@ get_elifs(If = {'if', Ann, Cond, Then, Else}, Elifs) ->
     end;
 get_elifs(Else, Elifs) -> {lists:reverse(Elifs), {else, Else}}.
 
-fmt(Fmt, Args) -> text(lists:flatten(io_lib:format(Fmt, Args))).
-term(X) -> fmt("~p", [X]).
-

src/aeso_syntax.erl

@@ -37,20 +37,24 @@
 -type decl() :: {contract, ann(), con(), [decl()]}
               | {namespace, ann(), con(), [decl()]}
               | {pragma, ann(), pragma()}
-              | {type_decl, ann(), id(), [tvar()]}
+              | {type_decl, ann(), id(), [tvar()]} % Only for error msgs
               | {type_def, ann(), id(), [tvar()], typedef()}
               | {fun_decl, ann(), id(), type()}
               | {fun_clauses, ann(), id(), type(), [letbind()]}
               | {block, ann(), [decl()]}
-              | letbind().
+              | letfun()
+              | letval(). % Only for error msgs
 
 -type compiler_version() :: [non_neg_integer()].
 
 -type pragma() :: {compiler, '==' | '<' | '>' | '=<' | '>=', compiler_version()}.
 
+
+-type letval() :: {letval, ann(), pat(), expr()}.
+-type letfun() :: {letfun, ann(), id(), [pat()], type(), expr()}.
 -type letbind()
-    :: {letval, ann(), pat(), expr()}
+    :: letfun()
-     | {letfun, ann(), id(), [pat()], type(), expr()}.
+     | letval().
 
 -type arg() :: {arg, ann(), id(), type()}.
 

src/aeso_syntax_utils.erl

@@ -45,7 +45,6 @@ fold(Alg = #alg{zero = Zero, plus = Plus, scoped = Scoped}, Fun, K, X) ->
             %% decl()
             {contract, _, _, Ds}     -> Decl(Ds);
             {namespace, _, _, Ds}    -> Decl(Ds);
-            {type_decl, _, I, _}     -> BindType(I);
             {type_def, _, I, _, D}   -> Plus(BindType(I), Decl(D));
             {fun_decl, _, _, T}      -> Type(T);
             {letval, _, P, E}        -> Scoped(BindExpr(P), Expr(E));

test/aeso_compiler_tests.erl

@@ -375,11 +375,15 @@ failing_contracts() ->
            "  r.foo : (gas : int, value : int) => Remote.themap\n"
            "against the expected type\n"
            "  (gas : int, value : int) => map(string, int)">>])
-    , ?TYPE_ERROR(bad_include_and_ns,
+    , ?TYPE_ERROR(not_toplevel_include,
-        [<<?Pos(2, 11)
+                  [<<?Pos(2, 11)
-           "Include of 'included.aes' at line 2, column 11\nnot allowed, include only allowed at top level.">>,
+                     "Include of 'included.aes' at line 2, column 11\nnot allowed, include only allowed at top level.">>])
-         <<?Pos(3, 13)
+    , ?TYPE_ERROR(not_toplevel_namespace,
-           "Nested namespace not allowed\nNamespace 'Foo' at line 3, column 13 not defined at top level.">>])
+                  [<<?Pos(2, 13)
+                     "Nested namespaces are not allowed\nNamespace 'Foo' at line 2, column 13 not defined at top level.">>])
+    , ?TYPE_ERROR(not_toplevel_contract,
+        [<<?Pos(2, 12)
+           "Nested contracts are not allowed\nContract 'Con' at line 2, column 12 not defined at top level.">>])
     , ?TYPE_ERROR(bad_address_literals,
         [<<?Pos(11, 5)
            "Cannot unify address\n"
@@ -612,6 +616,44 @@ 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\n"
+                     "Value this_is_illegal at line 2, column 7 could be replaced by 0-argument function">>])
+    , ?TYPE_ERROR(empty_typedecl,
+                  [<<?Pos(2, 8)
+                     "Empty type declarations are not supported\n"
+                     "Type t at line 2, column 8 lacks a definition">>])
+    , ?TYPE_ERROR(higher_kinded_type,
+                  [<<?Pos(2, 35)
+                     "Type 'm is a higher kinded type variable\n"
+                     "(takes another type as an argument)">>])
+    , ?TYPE_ERROR(bad_arity,
+                  [<<?Pos(3, 20)
+                     "Arity for id doesn't match. Expected 1, got 0">>,
+                   <<?Pos(3, 25)
+                     "Cannot unify int\n"
+                     "         and id\n"
+                     "when checking the type of the expression at line 3, column 25\n"
+                     "  123 : int\n"
+                     "against the expected type\n"
+                     "  id">>,
+                   <<?Pos(4, 20)
+                     "Arity for id doesn't match. Expected 1, got 2">>,
+                   <<?Pos(4, 35)
+                     "Cannot unify int\n"
+                     "         and id(int, int)\n"
+                     "when checking the type of the expression at line 4, column 35\n"
+                     "  123 : int\n"
+                     "against the expected type\n"
+                     "  id(int, int)">>])
+    , ?TYPE_ERROR(bad_unnamed_map_update_default,
+                  [<<?Pos(4, 17)
+                     "Invalid map update with default">>])
+    , ?TYPE_ERROR(non_functional_entrypoint,
+                  [<<?Pos(2, 14)
+                     "f at line 2, column 14 was declared with an invalid type int.\n"
+                     "Entrypoints and functions must have functional types">>])
     , ?TYPE_ERROR(bad_records,
         [<<?Pos(3, 16)
            "Mixed record fields and map keys in\n"

test/contracts/05_greeter.aes

@@ -58,8 +58,7 @@ contract Greeter =
 
     let state = { greeting = "Hello" }
 
-    let setGreeting =
+    function setGreeting(greeting: string) =
-        (greeting: string) =>
             state{ greeting = greeting }
 
 

test/contracts/all_syntax.aes

@@ -1,44 +1,78 @@
 // Try to cover all syntactic constructs.
+@compiler > 0
+@compiler =< 10.1.1.1.1.1.2.3.4
 
-contract AllSyntaxType =
-  type typeDecl /* bla */
-  type paramTypeDecl('a, 'b)
 
+namespace Ns =
+  datatype d('a) = D | S(int) | M('a, list('a), int)
+  private function fff() = 123
+
+  stateful entrypoint
+    f (1, x) = (_) => x
+
+payable contract AllSyntaxType =
   /** Multi-
     * line
     * comment
     */
-  function foo : _
+  stateful function foo : _
+  entrypoint bar : int => (int * 'a)
+
 
 contract AllSyntax =
 
-  type typeDecl = int
+  datatype mickiewicz = Adam | Mickiewicz
-  type paramTypeDecl('a, 'b) = (('a, 'b) => 'b) => list('a) => 'b => 'b
+  record goethe('a, 'b) = {
+    johann : int,
+    wolfgang : 'a,
+    von : 'a * 'b * int,
+    goethe : unit
+    }
+  type dante = Ns.d(int)
+  type shakespeare('a) = goethe('a, 'a)
 
-  record nestedRecord = { x : int }
+  type state = shakespeare(int)
-  record recordType = { z : nestedRecord, y : int }
-  datatype variantType('a) = None | Some('a)
 
-  let valWithType : map(int, int) => option(int) = (m) => Map.get(m, 42)
+  entrypoint init() = {
-  let valNoType =
+    johann = 1000,
-        if(valWithType(Map.empty) == None)
+    wolfgang = -10,
-          print(42 mod 10 * 5 / 3)
+    von = (2 + 2, 0, List.sum([x | k <- [1,2,3]
+                                 , let l = k + 1
+                                 , if(l < 10)
+                                 , let f(x) = x + 100
+                                 , Adam <- [Adam, Mickiewicz]
+                                 , let x = f(l)
+                                 ])),
+    goethe = () }
 
-  function funWithType(x : int, y) : int * list(int) = (x, 0 :: [y] ++ [])
+  function f() =
-  function funNoType() =
+     let kp = "nietzsche"
-    let foo = (x, y : bool) =>
+     let p = "Пушкин"
-                if (! (y && x =< 0x0b || true)) [x]
+     let k(x : bytes(8)) : bytes(8) = Bytes.to_int(#fedcba9876543210)
-                else [11..20]
-    let setY(r : recordType) : unit = r{ y = 5 }
-    let setX(r : recordType, x : int) : recordType = r { z.x = x }  // nested record update
-    let getY(r) = switch(r) {y = y} => y
-    switch (funWithType(1, -2))
-      (x, [y, z]) => bar({x = z, y = -y + - -z * (-1)})
-      (x, y :: _) => ()
 
-  let hash : address = #01ab0fff11
+     let f : () => address = () => ak_2gx9MEFxKvY9vMG5YnqnXWv1hCsX7rgnfvBLJS4aQurustR1rt
-  let b = false
+     if(Bits.test(Bits.all, 10))
-  let qcon = Mod.Con
+       abort("ohno")
-  let str = "blabla\nfoo"
+     if(true && false)
-  let chr = '"'
+       require(true, "ohyes")
+     elif(false || 2 == 2)
+       ()
+     else
+       ()
+     if(true) f(1,2)((1,2))
+     else switch(1::[1,2,3])
+       [] => 1
+       a::b => 123
+       1::2::3 => 123123
+       [2,3,4] => 1
+       _ => 13
+       1::[2] => 2138
+     put(state{johann = 1})
      
+     let m = {["foo"] = 19, /*hey wanna talk about inlined comments?*/ ["bar"] = 42}
+     let n = {}
+     m{ ["x" = 0] @ z = z + state.johann }
+
+     let sh : shakespeare(shakespeare(int)) =
+       {wolfgang = state}
+     sh{wolfgang.wolfgang = sh.wolfgang} // comment

test/contracts/bad_arity.aes

@@ -0,0 +1,4 @@
+contract C =
+  type id('a) = 'a
+  entrypoint f() : id = 123
+  entrypoint g() : id(int, int) = 123

test/contracts/bad_unnamed_map_update_default.aes

@@ -0,0 +1,5 @@
+contract C =
+  entrypoint f() =
+    let z = 123
+    {}{ [1 = 0] = z + 1 }
+    2

test/contracts/empty_typedecl.aes

@@ -0,0 +1,3 @@
+contract C =
+  type t
+  entrypoint f() = 123

test/contracts/higher_kinded_type.aes

@@ -0,0 +1,3 @@
+contract IWantToBelieve =
+  type stateT('s, 'm, 'a) = 's => 'm('a * 's)
+  entrypoint s() = 123

test/contracts/multi_sig.aes

@@ -15,7 +15,7 @@ contract MultiSig =
       | OwnerRemoved (address)          // of { .removedOwner : Address }
       | ReqChanged   (int)             // of { .newReq : int }
 
-    let maxOwners : int = 250
+    function maxOwners() : int = 250
 
     record state = { nRequired    : int
                  , nOwners      : int
@@ -68,7 +68,7 @@ contract MultiSig =
       switch(check_pending(callhash()))
         CheckFail(state') => { state = state' }
         CheckOk(state') =>
-            if(state.nOwners >= maxOwners) () /* TODO */
+            if(state.nOwners >= maxOwners()) () /* TODO */
             else
               let nOwners' = state'.nOwners + 1
               { state = state' { owners    = Map.insert(nOwners', newOwner, state'.owners)

test/contracts/non_functional_entrypoint.aes

@@ -0,0 +1,5 @@
+contract C1 =
+  entrypoint f : int
+
+contract C =
+  entrypoint f() = 123

test/contracts/not_toplevel_contract.aes

@@ -0,0 +1,6 @@
+namespace BadNs =
+  contract Con =
+    entrypoint e : () => int
+
+contract Con =
+  entrypoint foo() = 43

test/contracts/not_toplevel_include.aes

@@ -0,0 +1,5 @@
+namespace BadNs =
+  include "included.aes"
+
+contract Con =
+  entrypoint foo() = 43

test/contracts/not_toplevel_namespace.aes

@@ -1,5 +1,4 @@
-contract Bad =
+contract BadCon =
-  include "included.aes"
   namespace Foo =
     function foo() = 42
 

test/contracts/toplevel_let.aes

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

test/contracts/voting.aes

@@ -1,16 +1,3 @@
-
-/* Contract type */
-contract VotingType =
-  type state
-  function init            : list(string) => state
-
-  function giveRightToVote : address => unit
-  function delegate        : address => unit
-  function vote            : int => unit
-  function winnerName      : unit => string
-  function currentTally    : unit => list(string * int)
-
-/* Contract implementation */
 contract Voting =
 
   // Types