feat(compiler)!: Explicit abstract types (#1680)

Author: ospencer

compiler/src/formatting/format.re

@@ -4013,6 +4013,7 @@ and print_value_bind =
     switch (provide_flag) {
     | NotProvided => Doc.nil
     | Provided => Doc.text("provide ")
+    | Abstract => Doc.text("abstract ")
     };
   let recursive =
     switch (rec_flag) {
@@ -4627,6 +4628,7 @@ let data_print =
           switch ((expt: Asttypes.provide_flag)) {
           | NotProvided => Doc.nil
           | Provided => Doc.text("provide ")
+          | Abstract => Doc.text("abstract ")
           },
           print_data(~original_source, ~comments=data_comments, decl),
         ]);
@@ -4745,6 +4747,7 @@ let rec toplevel_print =
         switch (provide_flag) {
         | NotProvided => Doc.nil
         | Provided => Doc.text("provide ")
+        | Abstract => Doc.text("abstract ")
         };
       Doc.concat([
         provide,
@@ -4760,6 +4763,7 @@ let rec toplevel_print =
         switch (provide_flag) {
         | NotProvided => Doc.nil
         | Provided => Doc.text("provide ")
+        | Abstract => Doc.text("abstract ")
         };
       Doc.concat([
         provide,
@@ -4794,6 +4798,7 @@ let rec toplevel_print =
         switch (provide_flag) {
         | NotProvided => Doc.nil
         | Provided => Doc.text("provide ")
+        | Abstract => Doc.text("abstract ")
         };
       let cstr = type_exception.ptyexn_constructor;
 
@@ -4956,6 +4961,7 @@ let rec toplevel_print =
         switch (provide_flag) {
         | NotProvided => Doc.nil
         | Provided => Doc.text("provide ")
+        | Abstract => Doc.text("abstract ")
         };
 
       let start_after_brace = Doc.concat([Doc.hardLine, top_level_stmts]);

compiler/src/parsing/asttypes.re

@@ -64,7 +64,8 @@ and number_type =
 [@deriving (sexp, yojson)]
 type provide_flag =
   | NotProvided
-  | Provided;
+  | Provided
+  | Abstract;
 
 /** Marker for recursive/nonrecursive let bindings */
 

compiler/src/parsing/lexer.re

@@ -271,6 +271,7 @@ let rec token = lexbuf => {
   | "include" => positioned(INCLUDE)
   | "use" => positioned(USE)
   | "provide" => positioned(PROVIDE)
+  | "abstract" => positioned(ABSTRACT)
   | "except" => positioned(EXCEPT)
   | "from" => positioned(FROM)
   | "*" => positioned(STAR)

compiler/src/parsing/parser.messages

@@ -1591,7 +1591,19 @@ program: MODULE UIDENT EOL PROVIDE WHILE
 ## attributes PROVIDE
 ##
 
-Expected a let binding, data declaration, exception, or comma-separated list of identifiers surrounded by `{}`.
+Expected a let binding, type declaration, exception, or comma-separated list of identifiers surrounded by `{}`.
+
+program: MODULE UIDENT EOL ABSTRACT YIELD
+##
+## Ends in an error in state: 827.
+##
+## data_declaration_stmt -> ABSTRACT . data_declaration [ SEMI RBRACE EOL EOF COMMA ]
+##
+## The known suffix of the stack is as follows:
+## ABSTRACT
+##
+
+Expected a type declaration.
 
 program: MODULE UIDENT EOL FAIL WHEN
 ##

compiler/src/parsing/parser.mly

@@ -36,7 +36,7 @@ module Grain_parsing = struct end
 %token <string> PREFIX_150
 %token <string> INFIX_ASSIGNMENT_10
 
-%token ENUM RECORD TYPE MODULE INCLUDE USE PROVIDE FOREIGN WASM PRIMITIVE
+%token ENUM RECORD TYPE MODULE INCLUDE USE PROVIDE ABSTRACT FOREIGN WASM PRIMITIVE
 %token EXCEPT FROM STAR
 %token SLASH DASH PIPE
 %token EOL EOF
@@ -340,6 +340,7 @@ include_stmt:
   | INCLUDE file_path include_alias? { IncludeDeclaration.mk ~loc:(to_loc $loc) $2 $3 }
 
 data_declaration_stmt:
+  | ABSTRACT data_declaration { (Abstract, $2) }
   | PROVIDE data_declaration { (Provided, $2) }
   | data_declaration { (NotProvided, $1) }
 

compiler/src/parsing/parsetree.re

@@ -14,7 +14,8 @@ type loc('a) =
     loc: Location.t,
   };
 
-type provide_flag = Asttypes.provide_flag = | NotProvided | Provided;
+type provide_flag =
+  Asttypes.provide_flag = | NotProvided | Provided | Abstract;
 type rec_flag = Asttypes.rec_flag = | Nonrecursive | Recursive;
 type mut_flag = Asttypes.mut_flag = | Mutable | Immutable;
 

compiler/src/typed/ctype.re

@@ -2189,7 +2189,7 @@ let nondep_instance = (env, level, id, ty) => {
    list (nl2, tl2). raise Not_found if impossible */
 let complete_type_list = (~allow_absent=false, env, nl1, lv2, mty2, nl2, tl2) => {
   let id2 = Ident.create("Pkg");
-  let env' = Env.add_module(id2, mty2, None, env);
+  let env' = Env.add_module(id2, mty2, None, Location.dummy_loc, env);
   let rec complete = (nl1, ntl2) =>
     switch (nl1, ntl2) {
     | ([], _) => ntl2

compiler/src/typed/env.re

@@ -628,11 +628,7 @@ let strengthen =
                                                              module_type,
   );
 
-let md = (md_type, md_filepath) => {
-  md_type,
-  md_filepath,
-  md_loc: Location.dummy_loc,
-};
+let md = (md_type, md_filepath, md_loc) => {md_type, md_filepath, md_loc};
 
 let subst_modtype_maker = ((subst, md)) =>
   if (subst === Subst.identity) {
@@ -1072,7 +1068,11 @@ let find_module = (path, filename, env) =>
       let filename = Option.value(~default=Ident.name(id), filename);
       if (Ident.persistent(id) && !(filename == unit_source)) {
         let ps = find_pers_struct(~loc=Location.dummy_loc, filename);
-        md(TModSignature(Lazy.force(ps.ps_sig)), Some(filename));
+        md(
+          TModSignature(Lazy.force(ps.ps_sig)),
+          Some(filename),
+          Location.dummy_loc,
+        );
       } else {
         raise(Not_found);
       };
@@ -1926,8 +1926,8 @@ let add_module_declaration = (~arg=false, ~check, id, md, env) => {
 
 and add_modtype = (id, info, env) => store_modtype(id, info, env);
 
-let add_module = (~arg=?, id, mty, mf, env) =>
-  add_module_declaration(~check=false, ~arg?, id, md(mty, mf), env);
+let add_module = (~arg=?, id, mty, mf, mloc, env) =>
+  add_module_declaration(~check=false, ~arg?, id, md(mty, mf, mloc), env);
 
 let add_constructor = (id, desc, {constructors, _} as e) => {
   ...e,
@@ -1968,9 +1968,9 @@ and enter_module_declaration = (~arg=?, id, md, env) =>
    (id, add_functor_arg ?arg id env) */
 and enter_modtype = enter(store_modtype);
 
-let enter_module = (~arg=?, s, mty, env) => {
+let enter_module = (~arg=?, s, mty, mloc, env) => {
   let id = Ident.create(s);
-  (id, enter_module_declaration(~arg?, id, md(mty, None), env));
+  (id, enter_module_declaration(~arg?, id, md(mty, None, mloc), env));
 };
 
 /* Insertion of all components of a signature */
@@ -2077,7 +2077,7 @@ let include_module = (mod_name, mod_: Parsetree.include_declaration, env0) => {
       env0;
     } else {
       let mod_type = TModAlias(path);
-      env0 |> add_module(mod_ident, mod_type, filename);
+      env0 |> add_module(mod_ident, mod_type, filename, mod_.pinc_loc);
     }
   | _ =>
     let {ps_sig} = find_pers_struct(~loc=mod_.pinc_loc, mod_.pinc_path.txt);
@@ -2089,7 +2089,7 @@ let include_module = (mod_name, mod_: Parsetree.include_declaration, env0) => {
       {mtd_type: Some(mod_type), mtd_loc: mod_.pinc_loc},
       env0,
     )
-    |> add_module(mod_ident, mod_type, filename);
+    |> add_module(mod_ident, mod_type, filename, mod_.pinc_loc);
   };
 };
 

compiler/src/typed/env.rei

@@ -149,7 +149,8 @@ let add_constructor: (Ident.t, constructor_description, t) => t;
 
 /** Adds a constructor with the given name and description. */
 
-let add_module: (~arg: bool=?, Ident.t, module_type, option(string), t) => t;
+let add_module:
+  (~arg: bool=?, Ident.t, module_type, option(string), Location.t, t) => t;
 let add_module_declaration:
   (~arg: bool=?, ~check: bool, Ident.t, module_declaration, t) => t;
 let add_modtype: (Ident.t, modtype_declaration, t) => t;

compiler/src/typed/mtype.re

@@ -567,7 +567,11 @@ and remove_aliases_sig = (env, excl, sg) =>
 
     [
       TSigModule(id, {...md, md_type: mty}, rs),
-      ...remove_aliases_sig(Env.add_module(id, mty, None, env), excl, rem),
+      ...remove_aliases_sig(
+           Env.add_module(id, mty, None, md.md_loc, env),
+           excl,
+           rem,
+         ),
     ];
   | [TSigModType(id, mtd), ...rem] => [
       TSigModType(id, mtd),