feat(compiler): Partial function application

compiler/src/formatting/fmt.re

@@ -289,6 +289,8 @@ type formatter = {
   print_attribute: (formatter, attribute) => Doc.t,
   print_application_argument:
     (formatter, ~infix_wrap: t => t=?, application_argument) => Doc.t,
+  print_partial_application_argument:
+    (formatter, ~infix_wrap: t => t=?, partial_application_argument) => Doc.t,
   print_if:
     (
       formatter,
@@ -1157,6 +1159,32 @@ let print_application_argument = (fmt, ~infix_wrap=?, arg) => {
   ++ fmt.print_expression(fmt, ~infix_wrap?, arg.paa_expr);
 };
 
+let print_partial_application_argument = (fmt, ~infix_wrap=?, arg) => {
+  (
+    switch (arg.ppaa_label) {
+    | Unlabeled => empty
+    | Labeled({txt: label, loc: label_loc})
+    | Default({txt: label, loc: label_loc}) =>
+      string(label)
+      ++ string("=")
+      ++ fmt.print_comment_range(
+           fmt,
+           label_loc,
+           switch (arg.ppaa_expr) {
+           | ArgumentGiven(expr) => expr.pexp_loc
+           | ArgumentHole(loc) => loc
+           },
+         )
+    }
+  )
+  ++ (
+    switch (arg.ppaa_expr) {
+    | ArgumentGiven(expr) => fmt.print_expression(fmt, ~infix_wrap?, expr)
+    | ArgumentHole(_) => string("_")
+    }
+  );
+};
+
 let print_if =
     (fmt, ~force_blocks=false, ~loc, condition, true_branch, false_branch) =>
   if (force_blocks) {
@@ -1743,6 +1771,69 @@ let print_expression = (fmt, ~infix_wrap=d => group(indent(d)), expr) => {
              ++ break,
            ),
       )
+    | PExpPartial(fn, args) =>
+      string("partial")
+      ++ fmt.print_comment_range(
+           fmt,
+           ~allow_breaks=false,
+           ~none=space,
+           ~lead=space,
+           ~trail=space,
+           enclosing_start_location(expr.pexp_loc),
+           fn.pexp_loc,
+         )
+      ++ group(
+           fmt.print_grouped_access_expression(fmt, fn)
+           ++ parens(
+                indent(
+                  concat_map(
+                    ~lead=
+                      next =>
+                        fmt.print_comment_range(
+                          fmt,
+                          ~none=break,
+                          ~lead=if_broken(space, empty),
+                          ~trail=breakable_space,
+                          fn.pexp_loc,
+                          next.ppaa_loc,
+                        ),
+                    ~sep=
+                      (prev, next) =>
+                        fmt.print_comment_range(
+                          fmt,
+                          ~none=breakable_space,
+                          ~lead=space,
+                          ~trail=breakable_space,
+                          prev.ppaa_loc,
+                          next.ppaa_loc,
+                        ),
+                    ~trail=
+                      prev =>
+                        fmt.print_comment_range(
+                          fmt,
+                          ~block_end=true,
+                          ~lead=space,
+                          prev.ppaa_loc,
+                          enclosing_end_location(expr.pexp_loc),
+                        ),
+                    ~f=
+                      (~final, a) =>
+                        if (final) {
+                          group(
+                            fmt.print_partial_application_argument(fmt, a),
+                          );
+                        } else {
+                          group(
+                            fmt.print_partial_application_argument(fmt, a)
+                            ++ comma,
+                          );
+                        },
+                    args,
+                  ),
+                )
+                ++ break,
+              ),
+         )
     | PExpLambda(
         [
           {
@@ -4119,6 +4210,7 @@ let default_formatter: formatter = {
   print_match_branch,
   print_attribute,
   print_application_argument,
+  print_partial_application_argument,
   print_if,
   print_assignment,
   print_expression,

compiler/src/parsing/ast_helper.re

@@ -319,6 +319,31 @@ module Expression = {
     mk(~loc, ~core_loc, ~attributes?, PExpLambda(a, b));
   let apply = (~loc, ~core_loc, ~attributes=?, a, b) =>
     mk(~loc, ~core_loc, ~attributes?, PExpApp(a, b));
+  let partial_apply = (~loc, ~core_loc, ~attributes=?, a, b) =>
+    mk(~loc, ~core_loc, ~attributes?, PExpPartial(a, b));
+  let total_apply_args = (~loc, ~core_loc, ~attributes=?, a, b) => {
+    let args =
+      List.map(
+        arg =>
+          {
+            paa_loc: arg.ppaa_loc,
+            paa_expr:
+              switch (arg.ppaa_expr) {
+              | ArgumentGiven(expr) => expr
+              | ArgumentHole(_) =>
+                raise(
+                  SyntaxError(
+                    loc,
+                    "To use partial application, prefix the function call with `partial`.",
+                  ),
+                )
+              },
+            paa_label: arg.ppaa_label,
+          },
+        b,
+      );
+    mk(~loc, ~core_loc, ~attributes?, PExpApp(a, args));
+  };
   let construct = (~loc, ~core_loc, ~attributes=?, a, b) =>
     mk(~loc, ~core_loc, ~attributes?, PExpConstruct(a, b));
   let singleton_construct = (~loc, ~core_loc, ~attributes=?, a) =>

compiler/src/parsing/ast_helper.rei

@@ -374,6 +374,24 @@ module Expression: {
       list(application_argument)
     ) =>
     expression;
+  let partial_apply:
+    (
+      ~loc: loc,
+      ~core_loc: loc,
+      ~attributes: attributes=?,
+      expression,
+      list(partial_application_argument)
+    ) =>
+    expression;
+  let total_apply_args:
+    (
+      ~loc: loc,
+      ~core_loc: loc,
+      ~attributes: attributes=?,
+      expression,
+      list(partial_application_argument)
+    ) =>
+    expression;
   let construct:
     (
       ~loc: loc,

compiler/src/parsing/ast_mapper.re

@@ -252,6 +252,26 @@ module E = {
           el,
         ),
       )
+    | PExpPartial(e, el) =>
+      partial_apply(
+        ~loc,
+        ~core_loc,
+        ~attributes,
+        sub.expr(sub, e),
+        List.map(
+          arg =>
+            {
+              ppaa_label: arg.ppaa_label,
+              ppaa_expr:
+                switch (arg.ppaa_expr) {
+                | ArgumentGiven(expr) => ArgumentGiven(sub.expr(sub, expr))
+                | ArgumentHole(loc) => ArgumentHole(sub.location(sub, loc))
+                },
+              ppaa_loc: sub.location(sub, arg.ppaa_loc),
+            },
+          el,
+        ),
+      )
     | PExpConstruct(id, e) =>
       construct(
         ~loc,

compiler/src/parsing/lexer.re

@@ -291,6 +291,7 @@ let rec token = lexbuf => {
   | "catch" => positioned(CATCH)
   | "macro" => positioned(MACRO)
   | "yield" => positioned(YIELD)
+  | "partial" => positioned(PARTIAL)
   | "..." => positioned(ELLIPSIS)
   | "." => positioned(DOT)
   | "::" => positioned(COLONCOLON)

compiler/src/parsing/parser.messages

@@ -1133,6 +1133,26 @@ program: MODULE UIDENT EOL EOL WASMI64 THICKARROW
 ## In state 826, spurious reduction of production toplevel_stmt -> expr
 ## In state 819, spurious reduction of production lseparated_nonempty_list_inner(eos,toplevel_stmt) -> toplevel_stmt
 ##
+program: MODULE UIDENT EOL PARTIAL LIDENT LPAREN RPAREN YIELD
+##
+## Ends in an error in state: 743.
+##
+## app_expr -> left_accessor_expr lparen option(comma) rparen . [ LPAREN LBRACK DOT ]
+## partial_app_expr -> PARTIAL left_accessor_expr lparen option(comma) rparen . [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+##
+## The known suffix of the stack is as follows:
+## PARTIAL left_accessor_expr lparen option(comma) rparen
+##
+program: MODULE UIDENT EOL PARTIAL LIDENT LPAREN UIDENT RPAREN YIELD
+##
+## Ends in an error in state: 746.
+##
+## app_expr -> left_accessor_expr lparen lseparated_nonempty_list_inner(comma,app_arg) option(comma) rparen . [ LPAREN LBRACK DOT ]
+## partial_app_expr -> PARTIAL left_accessor_expr lparen lseparated_nonempty_list_inner(comma,app_arg) option(comma) rparen . [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+##
+## The known suffix of the stack is as follows:
+## PARTIAL left_accessor_expr lparen lseparated_nonempty_list_inner(comma,app_arg) option(comma) rparen
+##
 
 Expected a newline character to terminate the statement.
 
@@ -1840,6 +1860,16 @@ program: MODULE UIDENT EOL WHILE LPAREN UIDENT RPAREN EOL YIELD
 ## In state 1, spurious reduction of production nonempty_list(eol) -> EOL
 ## In state 5, spurious reduction of production eols -> nonempty_list(eol)
 ##
+program: MODULE UIDENT EOL PARTIAL YIELD
+##
+## Ends in an error in state: 124.
+##
+## partial_app_expr -> PARTIAL . left_accessor_expr lparen option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+## partial_app_expr -> PARTIAL . left_accessor_expr lparen lseparated_nonempty_list_inner(comma,app_arg) option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+##
+## The known suffix of the stack is as follows:
+## PARTIAL
+##
 
 Expected an expression.
 
@@ -3504,6 +3534,102 @@ program: MODULE UIDENT EOL IF WHILE
 
 Expected `(` followed by a condition expression.
 
+program: MODULE UIDENT EOL PARTIAL UIDENT YIELD
+##
+## Ends in an error in state: 740.
+##
+## app_expr -> left_accessor_expr . lparen option(comma) rparen [ LPAREN LBRACK DOT ]
+## app_expr -> left_accessor_expr . lparen lseparated_nonempty_list_inner(comma,app_arg) option(comma) rparen [ LPAREN LBRACK DOT ]
+## array_get -> left_accessor_expr . lbrack expr rbrack [ LPAREN LBRACK DOT ]
+## partial_app_expr -> PARTIAL left_accessor_expr . lparen option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+## partial_app_expr -> PARTIAL left_accessor_expr . lparen lseparated_nonempty_list_inner(comma,app_arg) option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+## record_get -> left_accessor_expr . DOT lid [ LPAREN LBRACK DOT ]
+## record_get -> left_accessor_expr . DOT eols lid [ LPAREN LBRACK DOT ]
+##
+## The known suffix of the stack is as follows:
+## PARTIAL left_accessor_expr
+##
+## WARNING: This example involves spurious reductions.
+## This implies that, although the LR(1) items shown above provide an
+## accurate view of the past (what has been recognized so far), they
+## may provide an INCOMPLETE view of the future (what was expected next).
+## In state 265, spurious reduction of production qualified_uid -> lseparated_nonempty_list_inner(dot,type_id_str)
+## In state 162, spurious reduction of production construct_expr -> qualified_uid
+## In state 312, spurious reduction of production left_accessor_expr -> construct_expr
+##
+
+Expected `(` followed by partial application arguments.
+
+program: MODULE UIDENT EOL PARTIAL LIDENT LPAREN YIELD
+##
+## Ends in an error in state: 741.
+##
+## app_expr -> left_accessor_expr lparen . option(comma) rparen [ LPAREN LBRACK DOT ]
+## app_expr -> left_accessor_expr lparen . lseparated_nonempty_list_inner(comma,app_arg) option(comma) rparen [ LPAREN LBRACK DOT ]
+## partial_app_expr -> PARTIAL left_accessor_expr lparen . option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+## partial_app_expr -> PARTIAL left_accessor_expr lparen . lseparated_nonempty_list_inner(comma,app_arg) option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+##
+## The known suffix of the stack is as follows:
+## PARTIAL left_accessor_expr lparen
+##
+## WARNING: This example involves spurious reductions.
+## This implies that, although the LR(1) items shown above provide an
+## accurate view of the past (what has been recognized so far), they
+## may provide an INCOMPLETE view of the future (what was expected next).
+## In state 4, spurious reduction of production lparen -> LPAREN
+##
+
+Expected an expression or `_`.
+
+program: MODULE UIDENT EOL PARTIAL LIDENT LPAREN COMMA YIELD
+##
+## Ends in an error in state: 742.
+##
+## app_expr -> left_accessor_expr lparen option(comma) . rparen [ LPAREN LBRACK DOT ]
+## partial_app_expr -> PARTIAL left_accessor_expr lparen option(comma) . rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+##
+## The known suffix of the stack is as follows:
+## PARTIAL left_accessor_expr lparen option(comma)
+##
+## WARNING: This example involves spurious reductions.
+## This implies that, although the LR(1) items shown above provide an
+## accurate view of the past (what has been recognized so far), they
+## may provide an INCOMPLETE view of the future (what was expected next).
+## In state 39, spurious reduction of production comma -> COMMA
+## In state 516, spurious reduction of production option(comma) -> comma
+##
+
+Expected a comma-separated list of partial application arguments or `)` to complete the partial application.
+
+program: MODULE UIDENT EOL PARTIAL LIDENT LPAREN UIDENT YIELD
+##
+## Ends in an error in state: 744.
+##
+## app_expr -> left_accessor_expr lparen lseparated_nonempty_list_inner(comma,app_arg) . option(comma) rparen [ LPAREN LBRACK DOT ]
+## lseparated_nonempty_list_inner(comma,app_arg) -> lseparated_nonempty_list_inner(comma,app_arg) . comma app_arg [ RPAREN EOL COMMA ]
+## partial_app_expr -> PARTIAL left_accessor_expr lparen lseparated_nonempty_list_inner(comma,app_arg) . option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LCARET INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 EOL EOF ELSE DASH COMMA COLON AND ]
+##
+## The known suffix of the stack is as follows:
+## PARTIAL left_accessor_expr lparen lseparated_nonempty_list_inner(comma,app_arg)
+##
+## WARNING: This example involves spurious reductions.
+## This implies that, although the LR(1) items shown above provide an
+## accurate view of the past (what has been recognized so far), they
+## may provide an INCOMPLETE view of the future (what was expected next).
+## In state 265, spurious reduction of production qualified_uid -> lseparated_nonempty_list_inner(dot,type_id_str)
+## In state 162, spurious reduction of production construct_expr -> qualified_uid
+## In state 312, spurious reduction of production left_accessor_expr -> construct_expr
+## In state 287, spurious reduction of production non_assign_expr -> left_accessor_expr
+## In state 263, spurious reduction of production non_binop_expr -> non_assign_expr
+## In state 194, spurious reduction of production annotated_expr -> non_binop_expr
+## In state 321, spurious reduction of production non_stmt_expr -> annotated_expr
+## In state 187, spurious reduction of production expr -> non_stmt_expr
+## In state 514, spurious reduction of production app_arg -> expr
+## In state 517, spurious reduction of production lseparated_nonempty_list_inner(comma,app_arg) -> app_arg
+##
+
+Expected a comma or `)` to complete the partial application.
+
 program: MODULE UIDENT EOL FOREIGN WASM LIDENT COLON UIDENT FROM YIELD
 ##
 ## Ends in an error in state: 753.
@@ -6617,21 +6743,22 @@ program: MODULE UIDENT EOL WASMI64 COLON UIDENT LCARET UIDENT RPAREN
 
 Expected `>` to complete the type.
 
-program: MODULE UIDENT EOL WASMI64 DOT LIDENT LPAREN UNDERSCORE
+program: MODULE UIDENT EOL BIGINT LPAREN YIELD
 ##
-## Ends in an error in state: 468.
+## Ends in an error in state: 279.
 ##
-## app_expr -> record_get lparen . option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LPAREN LCARET LBRACK INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 GETS EOL EOF ELSE DOT DASH COMMA COLON ]
-## app_expr -> record_get lparen . lseparated_nonempty_list_inner(comma,expr) option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LPAREN LCARET LBRACK INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 GETS EOL EOF ELSE DOT DASH COMMA COLON ]
+## app_expr -> left_accessor_expr lparen . option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LPAREN LCARET LBRACK INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 GETS EOL EOF ELSE DOT DASH COMMA COLON AND ]
+## app_expr -> left_accessor_expr lparen . lseparated_nonempty_list_inner(comma,app_arg) option(comma) rparen [ THICKARROW STAR SLASH SEMI RPAREN RCARET RBRACK RBRACE PIPE LPAREN LCARET LBRACK INFIX_90 INFIX_80 INFIX_70 INFIX_60 INFIX_50 INFIX_40 INFIX_30 INFIX_120 INFIX_110 INFIX_100 GETS EOL EOF ELSE DOT DASH COMMA COLON AND ]
 ##
 ## The known suffix of the stack is as follows:
-## record_get lparen
+## left_accessor_expr lparen
 ##
 ## WARNING: This example involves spurious reductions.
 ## This implies that, although the LR(1) items shown above provide an
 ## accurate view of the past (what has been recognized so far), they
 ## may provide an INCOMPLETE view of the future (what was expected next).
-## In state 2, spurious reduction of production lparen -> LPAREN
+## In state 1, spurious reduction of production nonempty_list(eol) -> EOL
+## In state 5, spurious reduction of production eols -> nonempty_list(eol)
 ##
 program: MODULE UIDENT EOL LBRACKRCARET RBRACK LPAREN COMMA WHILE
 ##