Merge pull request #354 from susliko/wildcard-bindings

Wildcards in tuple bindings

corpus/expressions.txt

@@ -1067,6 +1067,7 @@ object O {
    if (c) d.e }
   { a => implicit b => b }
   { (a: Int) ?=> (b: Int) => b }
+  { (_, a) => a }
 }
 
 --------------------------------------------------------------------------------
@@ -1157,7 +1158,15 @@ object O {
               (binding
                 (identifier)
                 (type_identifier)))
-            (identifier)))))))
+            (identifier))))
+      (block
+        (lambda_expression
+          (bindings
+            (binding
+              (wildcard))
+            (binding
+              (identifier)))
+          (identifier))))))
 
 ================================================================================
 Unit expressions

grammar.js

@@ -92,6 +92,8 @@ module.exports = grammar({
     // 'for'  operator_identifier  ':'  _annotated_type  •  ':'  …
     [$._type, $.compound_type],
     [$.lambda_expression, $.modifiers],
+    // _postfix_expression_choice  ':'  '('  wildcard  •  ':'  …
+    [$.binding, $._simple_type],
   ],
 
   word: $ => $._alpha_identifier,
@@ -1159,11 +1161,14 @@ module.exports = grammar({
 
     finally_clause: $ => prec.right(seq("finally", $._indentable_expression)),
 
+    /*
+     * Binding           ::=  (id | ‘_’) [‘:’ Type]
+     */
     binding: $ =>
       prec.dynamic(
         PREC.binding,
         seq(
-          field("name", $._identifier),
+          choice(field("name", $._identifier), $.wildcard),
           optional(seq(":", field("type", $._param_type))),
         ),
       ),