compiler: Match hole and add test for matching variants

Author: tekknolagi

compiler.py

@@ -160,6 +160,9 @@ def try_match(self, env: Env, arg: str, pattern: Object, fallthrough: str) -> En
             self._emit(f"if (!is_num({arg})) {{ goto {fallthrough}; }}")
             self._emit(f"if (num_value({arg}) != {pattern.value}) {{ goto {fallthrough}; }}")
             return {}
+        if isinstance(pattern, Hole):
+            self._emit(f"if (!is_hole({arg})) {{ goto {fallthrough}; }}")
+            return {}
         if isinstance(pattern, Variant):
             self.variant_tag(pattern.tag)  # register it for the big enum
             self._emit(f"if (!is_variant({arg})) {{ goto {fallthrough}; }}")

compiler_tests.py

@@ -52,6 +52,12 @@ def test_match_list(self) -> None:
     def test_match_record(self) -> None:
         self.assertEqual(self._run("f {a = 4, b = 5} . f = | {a = 1, b = 2} -> 3 | {a = 4, b = 5} -> 6"), "6\n")
 
+    def test_match_hole(self) -> None:
+        self.assertEqual(self._run("f () . f = | 1 -> 3 | () -> 4"), "4\n")
+
+    def test_match_variant(self) -> None:
+        self.assertEqual(self._run("f #foo () . f = | # bar 1 -> 3 | # foo () -> 4"), "4\n")
+
 
 if __name__ == "__main__":
     unittest.main()