Pattern matching for @nullable records.

Changes.md

@@ -4,11 +4,20 @@
 
 **Compiler**
 
-- Added support for `@new @variadic` (see https://github.com/rescript-lang/rescript-compiler/pull/5364) 
-- Added support for `@optional` fields in records (see https://github.com/rescript-lang/rescript-compiler/pull/5423)
+- Add support for `@new @variadic` (see https://github.com/rescript-lang/rescript-compiler/pull/5364) 
+- New records with `@optional` fields [#5423](https://github.com/rescript-lang/rescript-compiler/pull/5423) [#5452](https://github.com/rescript-lang/rescript-compiler/issues/5452)
 
 **Syntax**
 
+- Fix printing for inline nullary functor types [#477](https://github.com/rescript-lang/syntax/pull/477)
+- Fix stripping of quotes for empty poly variants [#474](https://github.com/rescript-lang/syntax/pull/474)
+- Implement syntax for arity zero vs arity one in uncurried application in [#139](https://github.com/rescript-lang/syntax/pull/139)
+- Fix parsing of first class module exprs as part of binary/ternary expr in [#256](https://github.com/rescript-lang/syntax/pull/256)
+
+**Libraries**
+
+- Several Belt libraries are now converted to ReScript syntax, with corresponding comments in Markdown format suitable for hovering.
+
 **Playground**
 
 - Added `jsoo_playground_main.ml` as the rescript-lang.org playground bundle entrypoint

jscomp/ml/typecore.ml

@@ -1149,7 +1149,26 @@ and type_pat_aux ~constrs ~labels ~no_existentials ~mode ~explode ~env
           Some (p0, p), expected_ty
         with Not_found -> None, newvar ()
       in
+      let label_is_optional ld =
+        match ld.lbl_repres with
+        | Record_optional_labels lbls -> Ext_list.mem_string lbls ld.lbl_name
+        | _ -> false in
+      let process_optional_label (ld, pat) =
+        let exp_optional_attr =
+          Ext_list.exists pat.ppat_attributes (fun ({txt },_) -> txt = "optional")
+        in
+        let isFromPamatch = match pat.ppat_desc with
+          | Ppat_construct ({txt = Lident s}, _) ->
+            String.length s >= 2 && s.[0] = '#' && s.[1] = '$'
+          | _ -> false
+        in
+        if label_is_optional ld && not exp_optional_attr && not isFromPamatch then
+          let lid = mknoloc (Longident.(Ldot (Lident "*predef*", "Some"))) in
+          Ast_helper.Pat.construct ~loc:pat.ppat_loc lid (Some pat)
+        else pat
+      in    
       let type_label_pat (label_lid, label, sarg) k =
+        let sarg = process_optional_label (label, sarg) in
         begin_def ();
         let (vars, ty_arg, ty_res) = instance_label false label in
         if vars = [] then end_def ();
@@ -1865,8 +1884,9 @@ and type_expect_ ?in_function ?(recarg=Rejected) env sexp ty_expected =
       Ext_list.exists e.pexp_attributes (fun ({txt },_) -> txt = "optional")
     in
     if label_is_optional ld && not exp_optional_attr then
-      let pexp_desc = Pexp_construct ({id with txt = Longident.Lident "Some"}, Some e)
-      in (id, ld, {e with pexp_desc})
+      let lid = mknoloc (Longident.(Ldot (Lident "*predef*", "Some"))) in
+      let e = Ast_helper.Exp.construct ~loc:e.pexp_loc lid (Some e)
+      in (id, ld, e)
     else (id, ld, e)
   in
   match sexp.pexp_desc with

jscomp/test/res_debug.js

@@ -15,6 +15,15 @@ var newrecord = Caml_obj.obj_dup(v0);
 
 newrecord.x = 3;
 
+function testMatch(v) {
+  var y = v.y;
+  if (y !== undefined) {
+    return y;
+  } else {
+    return 42;
+  }
+}
+
 var v2 = newrecord;
 
 var v1 = {
@@ -30,6 +39,7 @@ exports.f = f;
 exports.v0 = v0;
 exports.v2 = v2;
 exports.v1 = v1;
+exports.testMatch = testMatch;
 exports.h = h;
 exports.hey = hey;
 /*  Not a pure module */

jscomp/test/res_debug.res

@@ -44,6 +44,12 @@ let v1 : r = { x : 3
   , z : 3
 }
 
+let testMatch = v =>
+  switch v {
+  | {y} => y
+  | {y: @optional None} => 42
+  }
+
 let h = '😊'
 let hey = "hello, 世界"
 // failed to type check

lib/4.06.1/unstable/js_compiler.ml

@@ -40052,7 +40052,26 @@ and type_pat_aux ~constrs ~labels ~no_existentials ~mode ~explode ~env
           Some (p0, p), expected_ty
         with Not_found -> None, newvar ()
       in
+      let label_is_optional ld =
+        match ld.lbl_repres with
+        | Record_optional_labels lbls -> Ext_list.mem_string lbls ld.lbl_name
+        | _ -> false in
+      let process_optional_label (ld, pat) =
+        let exp_optional_attr =
+          Ext_list.exists pat.ppat_attributes (fun ({txt },_) -> txt = "optional")
+        in
+        let isFromPamatch = match pat.ppat_desc with
+          | Ppat_construct ({txt = Lident s}, _) ->
+            String.length s >= 2 && s.[0] = '#' && s.[1] = '$'
+          | _ -> false
+        in
+        if label_is_optional ld && not exp_optional_attr && not isFromPamatch then
+          let lid = mknoloc (Longident.(Ldot (Lident "*predef*", "Some"))) in
+          Ast_helper.Pat.construct ~loc:pat.ppat_loc lid (Some pat)
+        else pat
+      in    
       let type_label_pat (label_lid, label, sarg) k =
+        let sarg = process_optional_label (label, sarg) in
         begin_def ();
         let (vars, ty_arg, ty_res) = instance_label false label in
         if vars = [] then end_def ();
@@ -40768,8 +40787,9 @@ and type_expect_ ?in_function ?(recarg=Rejected) env sexp ty_expected =
       Ext_list.exists e.pexp_attributes (fun ({txt },_) -> txt = "optional")
     in
     if label_is_optional ld && not exp_optional_attr then
-      let pexp_desc = Pexp_construct ({id with txt = Longident.Lident "Some"}, Some e)
-      in (id, ld, {e with pexp_desc})
+      let lid = mknoloc (Longident.(Ldot (Lident "*predef*", "Some"))) in
+      let e = Ast_helper.Exp.construct ~loc:e.pexp_loc lid (Some e)
+      in (id, ld, e)
     else (id, ld, e)
   in
   match sexp.pexp_desc with

lib/4.06.1/unstable/js_playground_compiler.ml

@@ -40052,7 +40052,26 @@ and type_pat_aux ~constrs ~labels ~no_existentials ~mode ~explode ~env
           Some (p0, p), expected_ty
         with Not_found -> None, newvar ()
       in
+      let label_is_optional ld =
+        match ld.lbl_repres with
+        | Record_optional_labels lbls -> Ext_list.mem_string lbls ld.lbl_name
+        | _ -> false in
+      let process_optional_label (ld, pat) =
+        let exp_optional_attr =
+          Ext_list.exists pat.ppat_attributes (fun ({txt },_) -> txt = "optional")
+        in
+        let isFromPamatch = match pat.ppat_desc with
+          | Ppat_construct ({txt = Lident s}, _) ->
+            String.length s >= 2 && s.[0] = '#' && s.[1] = '$'
+          | _ -> false
+        in
+        if label_is_optional ld && not exp_optional_attr && not isFromPamatch then
+          let lid = mknoloc (Longident.(Ldot (Lident "*predef*", "Some"))) in
+          Ast_helper.Pat.construct ~loc:pat.ppat_loc lid (Some pat)
+        else pat
+      in    
       let type_label_pat (label_lid, label, sarg) k =
+        let sarg = process_optional_label (label, sarg) in
         begin_def ();
         let (vars, ty_arg, ty_res) = instance_label false label in
         if vars = [] then end_def ();
@@ -40768,8 +40787,9 @@ and type_expect_ ?in_function ?(recarg=Rejected) env sexp ty_expected =
       Ext_list.exists e.pexp_attributes (fun ({txt },_) -> txt = "optional")
     in
     if label_is_optional ld && not exp_optional_attr then
-      let pexp_desc = Pexp_construct ({id with txt = Longident.Lident "Some"}, Some e)
-      in (id, ld, {e with pexp_desc})
+      let lid = mknoloc (Longident.(Ldot (Lident "*predef*", "Some"))) in
+      let e = Ast_helper.Exp.construct ~loc:e.pexp_loc lid (Some e)
+      in (id, ld, e)
     else (id, ld, e)
   in
   match sexp.pexp_desc with

lib/4.06.1/whole_compiler.ml

@@ -214583,7 +214583,26 @@ and type_pat_aux ~constrs ~labels ~no_existentials ~mode ~explode ~env
           Some (p0, p), expected_ty
         with Not_found -> None, newvar ()
       in
+      let label_is_optional ld =
+        match ld.lbl_repres with
+        | Record_optional_labels lbls -> Ext_list.mem_string lbls ld.lbl_name
+        | _ -> false in
+      let process_optional_label (ld, pat) =
+        let exp_optional_attr =
+          Ext_list.exists pat.ppat_attributes (fun ({txt },_) -> txt = "optional")
+        in
+        let isFromPamatch = match pat.ppat_desc with
+          | Ppat_construct ({txt = Lident s}, _) ->
+            String.length s >= 2 && s.[0] = '#' && s.[1] = '$'
+          | _ -> false
+        in
+        if label_is_optional ld && not exp_optional_attr && not isFromPamatch then
+          let lid = mknoloc (Longident.(Ldot (Lident "*predef*", "Some"))) in
+          Ast_helper.Pat.construct ~loc:pat.ppat_loc lid (Some pat)
+        else pat
+      in    
       let type_label_pat (label_lid, label, sarg) k =
+        let sarg = process_optional_label (label, sarg) in
         begin_def ();
         let (vars, ty_arg, ty_res) = instance_label false label in
         if vars = [] then end_def ();
@@ -215299,8 +215318,9 @@ and type_expect_ ?in_function ?(recarg=Rejected) env sexp ty_expected =
       Ext_list.exists e.pexp_attributes (fun ({txt },_) -> txt = "optional")
     in
     if label_is_optional ld && not exp_optional_attr then
-      let pexp_desc = Pexp_construct ({id with txt = Longident.Lident "Some"}, Some e)
-      in (id, ld, {e with pexp_desc})
+      let lid = mknoloc (Longident.(Ldot (Lident "*predef*", "Some"))) in
+      let e = Ast_helper.Exp.construct ~loc:e.pexp_loc lid (Some e)
+      in (id, ld, e)
     else (id, ld, e)
   in
   match sexp.pexp_desc with