Implement [a..b]

CHANGELOG.md

@@ -6,6 +6,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Added
+- Added the `[a..b]` language construct, returning the list of numbers between
+  `a` and `b` (inclusive). Returns the empty list if `a` > `b`.
 ### Changed
 ### Removed
 

priv/stdlib/ListInternal.aes

@@ -7,3 +7,10 @@ namespace ListInternal =
       []      => []
       x :: xs => f(x) ++ flat_map(f, xs)
 
+  // -- From..to ---------------------------------------------------------------
+
+  function from_to(a : int, b : int) : list(int) = from_to_(a, b, [])
+
+  private function from_to_(a, b, acc) =
+    if (a > b) acc else from_to_(a, b - 1, b :: acc)
+

src/aeso_ast_infer_types.erl

@@ -1352,6 +1352,9 @@ infer_infix({RelOp, As})
     T = fresh_uvar(As),     %% allow any type here, check in ast_to_icode that we have comparison for it
     Bool = {id, As, "bool"},
     {fun_t, As, [], [T, T], Bool};
+infer_infix({'..', As}) ->
+    Int = {id, As, "int"},
+    {fun_t, As, [], [Int, Int], {app_t, As, {id, As, "list"}, [Int]}};
 infer_infix({'::', As}) ->
     ElemType = fresh_uvar(As),
     ListType = {app_t, As, {id, As, "list"}, [ElemType]},

src/aeso_ast_to_fcode.erl

@@ -453,12 +453,16 @@ expr_to_fcode(Env, _Type, {list, _, Es}) ->
     lists:foldr(fun(E, L) -> {op, '::', [expr_to_fcode(Env, E), L]} end,
                 nil, Es);
 
+expr_to_fcode(Env, _Type, {app, _, {'..', _}, [A, B]}) ->
+    {def_u, FromTo, _} = resolve_fun(Env, ["ListInternal", "from_to"]),
+    {def, FromTo, [expr_to_fcode(Env, A), expr_to_fcode(Env, B)]};
+
 expr_to_fcode(Env, _Type, {list_comp, _, Yield, []}) ->
     {op, '::', [expr_to_fcode(Env, Yield), nil]};
 expr_to_fcode(Env, _Type, {list_comp, As, Yield, [{comprehension_bind, {typed, {id, _, Arg}, _}, BindExpr}|Rest]}) ->
     Env1 = bind_var(Env, Arg),
     Bind = {lam, [Arg], expr_to_fcode(Env1, {list_comp, As, Yield, Rest})},
-    {def_u, FlatMap, _} = resolve_fun(Env, ["List", "flat_map"]),
+    {def_u, FlatMap, _} = resolve_fun(Env, ["ListInternal", "flat_map"]),
     {def, FlatMap, [Bind, expr_to_fcode(Env, BindExpr)]};
 expr_to_fcode(Env, Type, {list_comp, As, Yield, [{comprehension_if, _, Cond}|Rest]}) ->
     make_if(expr_to_fcode(Env, Cond),

src/aeso_ast_to_icode.erl

@@ -523,6 +523,10 @@ ast_body({app, _, {typed, _, {con, _, Name}, _}, Args}, Icode) ->
 ast_body({app, _, {typed, _, {qcon, _, Name}, _}, Args}, Icode) ->
     Tag = aeso_icode:get_constructor_tag(Name, Icode),
     #tuple{cpts = [#integer{value = Tag} | [ ast_body(Arg, Icode) || Arg <- Args ]]};
+ast_body({app, _, {'..', _}, [A, B]}, Icode) ->
+    #funcall
+    { function = #var_ref{ name = ["ListInternal", "from_to"] }
+    , args     = [ast_body(A, Icode), ast_body(B, Icode)] };
 ast_body({app,As,Fun,Args}, Icode) ->
     case aeso_syntax:get_ann(format, As) of
         infix  ->
@@ -541,7 +545,7 @@ ast_body({list_comp, _, Yield, []}, Icode) ->
     #list{elems = [ast_body(Yield, Icode)]};
 ast_body({list_comp, As, Yield, [{comprehension_bind, {typed, Arg, ArgType}, BindExpr}|Rest]}, Icode) ->
     #funcall
-        { function = #var_ref{ name = ["List", "flat_map"] }
+        { function = #var_ref{ name = ["ListInternal", "flat_map"] }
         , args =
               [ #lambda{ args=[#arg{name = ast_id(Arg), type = ast_type(ArgType, Icode)}]
                        , body = ast_body({list_comp, As, Yield, Rest}, Icode)