[merge] Support opaque resources

Fixes #360

* modules:
  [tests] Add a test for invalid use of opaque resources
  [compiler] Write opaque resources to interface files
  [compiler] Handle opaque resources in interfaces
  [compiler/parse] Update an old comment in the parser
  [docs] Add opaque keyword to resource definitions
  [tests] Add a test for opaque resource syntax
  [compiler/ast] Resources use the sharing_opaque type
  [compiler/parse] Refactor how exports are parsed
  [compiler] Rename sharing_type to sharing_opaque

docs/plasma_ref.txt

@@ -649,7 +649,7 @@ a time.
 == Resources
 
 ----
-ResourceDefinition := 'export'? 'resource' Ident 'from' QualifiedIdent
+ResourceDefinition := ('export' 'opaque'?)? 'resource' Ident 'from' QualifiedIdent
 ----
 
 This defines a new resource.  The resource has the given name and is a

src/ast.m

@@ -44,7 +44,12 @@
     ;       ast_pragma(ast_pragma).
 
 :- type ast_interface_entry
-    --->    asti_resource(q_name, ast_resource)
+    --->    asti_resource(
+                q_name,
+
+                % Opaque resources won't have a definition.
+                maybe(ast_resource)
+            )
     ;       asti_type(q_name, ast_type(q_name))
     ;       asti_function(q_name, ast_function_decl).
 
@@ -63,7 +68,7 @@
     --->    ast_type(
                 at_params           :: list(string),
                 at_costructors      :: list(at_constructor(Name)),
-                at_export           :: sharing_type,
+                at_export           :: sharing_opaque,
                 at_context          :: context
             )
             % An abstractly-imported type.
@@ -77,7 +82,7 @@
 :- type ast_resource
     --->    ast_resource(
                 ar_from             :: q_name,
-                ar_sharing          :: sharing,
+                ar_sharing          :: sharing_opaque,
                 ar_context          :: context
             ).
 

src/builtins.m

@@ -212,7 +212,7 @@
     MaybeName = nq_name_det("Maybe"),
     core_set_type(MaybeType,
         type_init(q_name_append(builtin_module_name, MaybeName),
-            [MaybeParamName], [NoneId, SomeId], st_private, i_imported,
+            [MaybeParamName], [NoneId, SomeId], so_private, i_imported,
             builtin_context),
         !Core),
     root_name(MaybeName, bi_type(MaybeType, arity(1)), !Map).
@@ -291,7 +291,7 @@
     BoolName = nq_name_det("Bool"),
     core_set_type(BoolId,
         type_init(q_name_append(builtin_module_name, BoolName), [],
-            [FalseId, TrueId], st_private, i_imported, builtin_context),
+            [FalseId, TrueId], so_private, i_imported, builtin_context),
         !Core),
     root_name(BoolName, bi_type(BoolId, arity(0)), !Map),
 
@@ -472,7 +472,7 @@
 
     core_set_type(ListId,
         type_init(q_name_append_str(builtin_module_name, "List"), [T],
-            [NilId, ConsId], st_private, i_imported, builtin_context),
+            [NilId, ConsId], so_private, i_imported, builtin_context),
         !Core),
 
     root_name(nq_name_det("List"), bi_type(ListId, arity(1)), !Map).
@@ -515,7 +515,7 @@
     IOResultName = nq_name_det("IOResult"),
     core_set_type(IOResultType,
         type_init(q_name_append(builtin_module_name, IOResultName),
-            [OkParamName], [OkId, EOFId], st_private, i_imported, builtin_context),
+            [OkParamName], [OkId, EOFId], so_private, i_imported, builtin_context),
         !Core),
     root_name(IOResultName, bi_type(IOResultType, arity(1)), !Map),
 
@@ -558,7 +558,7 @@
     EnvironmentName = nq_name_det("Environment"),
     EnvironmentQName = q_name_append(builtin_module_name, EnvironmentName),
     register_builtin_resource(EnvironmentName,
-        r_other(EnvironmentQName, RIO, s_private, i_imported, builtin_context),
+        r_other(EnvironmentQName, RIO, so_private, i_imported, builtin_context),
         REnv, !Map, !Core),
     SetenvName = q_name_append_str(builtin_module_name, "setenv"),
     register_builtin_func_root(nq_name_det("setenv"),
@@ -571,7 +571,7 @@
     TimeName = nq_name_det("Time"),
     TimeQName = q_name_append(builtin_module_name, TimeName),
     register_builtin_resource(TimeName,
-        r_other(TimeQName, RIO, s_private, i_imported, builtin_context),
+        r_other(TimeQName, RIO, so_private, i_imported, builtin_context),
         RTime, !Map, !Core),
     GettimeofdayName = q_name_append_str(builtin_module_name, "gettimeofday"),
     register_builtin_func_builtin(nq_name_det("gettimeofday"),
@@ -615,7 +615,7 @@
     core_set_type(CodepointCategoryId,
         type_init(q_name_append(builtin_module_name,
                 CodepointCategoryTypeName), [],
-            [WhitespaceId, OtherId], st_private, i_imported, builtin_context),
+            [WhitespaceId, OtherId], so_private, i_imported, builtin_context),
         !Core),
     root_name(CodepointCategoryTypeName,
         bi_type(CodepointCategoryId, arity(0)), !Map),

src/common_types.m

@@ -22,13 +22,13 @@
     --->    s_public
     ;       s_private.
 
-    % Types have a 3rd option, to export the type name but not its details
-    % (constructors & fields).
+    % Types and resources have a 3rd option, to export the name but not its
+    % details.
     %
-:- type sharing_type
-    --->    st_private
-    ;       st_public
-    ;       st_public_opaque.
+:- type sharing_opaque
+    --->    so_private
+    ;       so_public
+    ;       so_public_opaque.
 
     % Is an exported function an entrypoint.
     %

src/compile.m

@@ -298,10 +298,12 @@
     ( if
         env_add_resource(q_name(Name), ResId, !Env),
         Sharing = Res ^ ar_sharing,
-        ( Sharing = s_public,
+        (   ( Sharing = so_public
+            ; Sharing = so_public_opaque
+            ),
             env_add_resource(q_name_append(ModuleName, Name), ResId,
                 !ImportEnv)
-        ; Sharing = s_private
+        ; Sharing = so_private
         )
     then
         true
@@ -320,12 +322,12 @@
         env_add_type(q_name(Name), Arity, TypeId, !Env),
         Sharing = Type ^ at_export,
         (
-            ( Sharing = st_public
-            ; Sharing = st_public_opaque
+            ( Sharing = so_public
+            ; Sharing = so_public_opaque
             ),
             env_add_type(q_name_append(ModuleName, Name), Arity, TypeId,
                 !ImportEnv)
-        ; Sharing = st_private
+        ; Sharing = so_private
         )
     then
         true
@@ -344,15 +346,18 @@
         filter_entries(Entries, _, Resources0, Types0, _, _),
 
         filter_map((pred(NamedRes::in, Name::out) is semidet :-
-                NamedRes = nq_named(NQName, ast_resource(_, s_public, _)),
+                NamedRes = nq_named(NQName, ast_resource(_, Sharing, _)),
+                ( Sharing = so_public
+                ; Sharing = so_public_opaque
+                ),
                 Name = q_name_append(ModuleName, NQName)
             ),
             Resources0, Resources),
 
         filter_map((pred(NamedRes::in, {Name, Arity}::out) is semidet :-
                 NamedRes = nq_named(NQName, ast_type(Params, _, Sharing, _)),
-                ( Sharing = st_public
-                ; Sharing = st_public_opaque
+                ( Sharing = so_public
+                ; Sharing = so_public_opaque
                 ),
                 Name = q_name_append(ModuleName, NQName),
                 Arity = arity(length(Params))

src/core.m

@@ -280,9 +280,7 @@
 
 type_is_exported(_ - Type) :-
     Sharing = utype_get_sharing(Type),
-    ( Sharing = st_public
-    ; Sharing = st_public_opaque
-    ).
+    sharing_is_exported(Sharing).
 
 core_get_type(Core, TypeId) = Type :-
     lookup(Core ^ c_types, TypeId, Type).
@@ -334,6 +332,12 @@
 
 :- pred resource_is_exported(pair(resource_id, resource)::in) is semidet.
 
-resource_is_exported(_ - r_other(_, _, s_public, _, _)).
+resource_is_exported(_ - r_other(_, _, Sharing, _, _)) :-
+    sharing_is_exported(Sharing).
+
+:- pred sharing_is_exported(sharing_opaque::in) is semidet.
+
+sharing_is_exported(so_public).
+sharing_is_exported(so_public_opaque).
 
 %-----------------------------------------------------------------------%

src/core.pretty.m

@@ -37,7 +37,7 @@
     % we probably should parameterise it and other pretty-printer functions
     % here.
     %
-:- func type_decl_pretty(core, user_type) = pretty.
+:- func type_interface_pretty(core, user_type) = pretty.
 
     % Print the argument parts of a function type.  You can either put
     % "func" in front of this or the name of the variable at a call site.
@@ -61,7 +61,7 @@
 
     % Pretty print a resource definition.
     %
-:- func resource_decl_pretty(core, resource) = pretty.
+:- func resource_interface_pretty(core, resource) = pretty.
 
 :- func constructor_name_pretty(core, set(ctor_id)) = pretty.
 
@@ -88,11 +88,11 @@
 
 %-----------------------------------------------------------------------%
 
-type_decl_pretty(Core, Type) = p_expr(Pretty) :-
+type_interface_pretty(Core, Type) = p_expr(Pretty) :-
     Sharing = utype_get_sharing(Type),
-    ( Sharing = st_private,
+    ( Sharing = so_private,
         unexpected($file, $pred, "st_private")
-    ; Sharing = st_public,
+    ; Sharing = so_public,
         MaybeParams = utype_get_params(Type),
         ( MaybeParams = yes(Params)
         ; MaybeParams = no,
@@ -112,7 +112,7 @@
             unexpected($file, $pred, "Public type without constructors")
         ),
         Pretty = PrettyHead ++ PrettyBody
-    ; Sharing = st_public_opaque,
+    ; Sharing = so_public_opaque,
         Pretty = [p_str("type "),
             q_name_pretty(utype_get_name(Type)),
             p_str("/"),
@@ -405,11 +405,18 @@
 resource_pretty(Core, ResId) =
     p_str(resource_to_string(core_get_resource(Core, ResId))).
 
-resource_decl_pretty(_, r_io) = unexpected($file, $pred, "IO").
-resource_decl_pretty(Core, r_other(Name, From, _, _, _)) =
-    p_expr([p_str("resource"), p_spc, q_name_pretty(Name),
-        p_spc, p_str("from"), p_spc, resource_pretty(Core, From)]).
-resource_decl_pretty(_, r_abstract(Name)) =
+resource_interface_pretty(_, r_io) = unexpected($file, $pred, "IO").
+resource_interface_pretty(Core, r_other(Name, From, Sharing, _, _)) = Pretty :-
+    ( Sharing = so_public,
+        Pretty = p_expr([p_str("resource"), p_spc, q_name_pretty(Name),
+            p_spc, p_str("from"), p_spc, resource_pretty(Core, From)])
+    ; Sharing = so_public_opaque,
+        Pretty = p_expr([p_str("resource"), p_spc, q_name_pretty(Name)])
+    ; Sharing = so_private,
+        Pretty = p_empty
+    ).
+
+resource_interface_pretty(_, r_abstract(Name)) =
     p_expr([p_str("resource"), p_spc, q_name_pretty(Name)]).
 
 %-----------------------------------------------------------------------%

src/core.resource.m

@@ -22,7 +22,7 @@
     ;       r_other(
                 ro_name     :: q_name,
                 ro_from     :: resource_id,
-                ro_sharing  :: sharing,
+                ro_sharing  :: sharing_opaque,
                 ro_imported :: imported,
                 ro_context  :: context
             )

src/core.types.m

@@ -61,7 +61,7 @@
 
 :- type user_type.
 
-:- func type_init(q_name, list(string), list(ctor_id), sharing_type,
+:- func type_init(q_name, list(string), list(ctor_id), sharing_opaque,
     imported, context) = user_type.
 
 :- func type_init_abstract(q_name, arity, context) = user_type.
@@ -72,7 +72,7 @@
 
 :- func utype_get_ctors(user_type) = maybe(list(ctor_id)).
 
-:- func utype_get_sharing(user_type) = sharing_type.
+:- func utype_get_sharing(user_type) = sharing_opaque.
 
 :- func utype_get_imported(user_type) = imported.
 
@@ -162,7 +162,7 @@
                 t_symbol        :: q_name,
                 t_params        :: list(string),
                 t_ctors         :: list(ctor_id),
-                t_sharing       :: sharing_type,
+                t_sharing       :: sharing_opaque,
                 t_imported      :: imported,
                 t_context       :: context
             )
@@ -191,7 +191,7 @@
     ).
 
 utype_get_sharing(user_type(_, _, _, Sharing, _, _)) = Sharing.
-utype_get_sharing(abstract_type(_, _, _)) = st_private.
+utype_get_sharing(abstract_type(_, _, _)) = so_private.
 
 utype_get_imported(user_type(_, _, _, _, Imported, _)) = Imported.
 utype_get_imported(abstract_type(_, _, _)) = i_imported.