key in map syntax

compiler/main.v

@@ -244,6 +244,7 @@ typedef map map_string;
 #define _PUSH(arr, val, tmp, tmp_typ) {tmp_typ tmp = (val); array__push(arr, &tmp);}
 #define _PUSH_MANY(arr, val, tmp, tmp_typ) {tmp_typ tmp = (val); array__push_many(arr, tmp.data, tmp.len);}
 #define _IN(typ, val, arr) array_##typ##_contains(arr, val) 
+#define _IN_MAP(val, m) map__exists(m, val) 
 #define ALLOC_INIT(type, ...) (type *)memdup((type[]){ __VA_ARGS__ }, sizeof(type)) 
 
 //================================== GLOBALS =================================*/   

compiler/parser.v

@@ -1970,22 +1970,29 @@ fn (p mut Parser) expression() string {
 			return 'int'
 		}
 	}
-	// a in [1,2,3]
+	// `a in [1, 2, 3]` 
+	// `key in map` 
 	if p.tok == .key_in {
 		p.fgen(' ')
 		p.check(.key_in)
 		p.fgen(' ')
 		p.gen(', ')
 		arr_typ := p.expression()
-		if !arr_typ.starts_with('array_') {
-			p.error('`in` requires an array')
+		is_map := arr_typ.starts_with('map_') 
+		if !arr_typ.starts_with('array_') && !is_map { 
+			p.error('`in` requires an array/map')
 		}
 		T := p.table.find_type(arr_typ)
-		if !T.has_method('contains') {
+		if !is_map && !T.has_method('contains') {
 			p.error('$arr_typ has no method `contains`')
 		}
-		// `typ` is element type
+		// `typ` is element's type
+		if is_map {
+			p.cgen.set_placeholder(ph, '_IN_MAP( ')
+		} 
+		else { 
 			p.cgen.set_placeholder(ph, '_IN($typ, ')
+		} 
 		p.gen(')')
 		return 'bool'
 	}

compiler/table.v

@@ -699,7 +699,7 @@ fn new_file_import_table(file_path string) *FileImportTable {
 }
 
 fn (fit &FileImportTable) known_import(mod string) bool {
-	return fit.imports.exists(mod) || fit.is_aliased(mod)
+	return mod in fit.imports || fit.is_aliased(mod)
 }
 
 fn (fit mut FileImportTable) register_import(mod string) {
@@ -707,7 +707,7 @@ fn (fit mut FileImportTable) register_import(mod string) {
 }
 
 fn (fit mut FileImportTable) register_alias(alias string, mod string) {
-	if fit.imports.exists(alias) {
+	if alias in fit.imports { 
 		panic('cannot import $mod as $alias: import name $alias already in use in "${fit.file_path}".')
 		return 
 	} 
@@ -715,7 +715,7 @@ fn (fit mut FileImportTable) register_alias(alias string, mod string) {
 }
 
 fn (fit &FileImportTable) known_alias(alias string) bool {
-	return fit.imports.exists(alias)
+	return alias in fit.imports 
 }
 
 fn (fit &FileImportTable) is_aliased(mod string) bool {
@@ -728,8 +728,5 @@ fn (fit &FileImportTable) is_aliased(mod string) bool {
 }
 
 fn (fit &FileImportTable) resolve_alias(alias string) string {
-	if fit.imports.exists(alias) {
 	return fit.imports[alias]
-	}
-	return ''
 }

vlib/builtin/map.v

@@ -170,6 +170,11 @@ fn (m map) get(key string, out voidptr) bool {
 }
 
 pub fn (m map) exists(key string) bool {
+	panic('map.exists(key) was removed from the language. Use `key in map` instead.') 
+	return false 
+}
+
+fn (m map) _exists(key string) bool {
 	return !isnil(m.root) && m.root.find2(key, m.element_size) 
 }
 

vlib/builtin/map_test.v

@@ -21,6 +21,7 @@ fn test_map() {
 	assert m['hi'] == 80
 	assert m['hello'] == 101 
 	assert m.size == 2 
+	assert 'hi' in m 
 	mut sum := 0
 	mut key_sum := '' 
 	// Test `for in`