operator ? to sign an argument as not-required

int sqr(int x) => x ** 2;

sqr(2); // 4
sqr();  // Exception

int sqrt(int x?) => x ** 2;
sqr();  // NaN

README.md

@@ -378,16 +378,7 @@ Future plans
 		int data.getFriendsCount() => this.friends.length;
 	 
 - operator `?.`. status: done
-- Negate array accessor ( getter )
+- operator `?` to sign an argument as not-required. status: done
- 
-		arr[-1]; // last element
-
-	only for static negate index, for other cases you can use `%` unary prefix:
-	
-		int index = -10;
-		arr[%index] = 34; // arr[index %% arr.length];
-
-- operator `?` to sign an argument as not-required
 
 		int sqr(int x) => x ** 2;
 		
@@ -397,6 +388,15 @@ Future plans
 		int sqrt(int x?) => x ** 2;
 		sqr();  // NaN
 
+- Negate array accessor ( getter )
+ 
+		arr[-1]; // last element
+
+	only for static negate index, for other cases you can use `%` unary prefix:
+	
+		int index = -10;
+		arr[%index] = 34; // arr[index %% arr.length];
+
 - static typing	
 - `@use` expressions
 		

lib/ast.js

@@ -421,7 +421,7 @@ Cola.AST_Namedarg = Cola.DEFNODE("Namedarg", "start end name value", {
     }
 }, Cola.AST_SymbolRef);
 
-Cola.AST_ArgDef = Cola.DEFNODE("ArgDef", "start end name type argtype defval", {
+Cola.AST_ArgDef = Cola.DEFNODE("ArgDef", "start end name type argtype defval required", {
     $iscola: true,
     $documentation: "A function argument expression",
     $propdoc: {

lib/parse.js

@@ -1310,14 +1310,22 @@ Cola.Parser.prototype.for_in = function (init) {
 };
 
 Cola.Parser.prototype.as_funcarg = function(splatedexist) {
-    var name = this.as_symbol(Cola.AST_SymbolFunarg), type = name, argtype = 'positional', defval = new Cola.AST_Noop();
+    var name = this.as_symbol(Cola.AST_SymbolFunarg), type = name, argtype = 'positional', defval = new Cola.AST_Noop, required = true;
+
     if(this.is("name")) name = this.as_symbol(Cola.AST_SymbolFunarg);
-    if(this.is("punc", "...")){
+
+    if(this.is("operator", "?")){
+        required = false;
+        this.next();
+    }
+
+    if(this.is("punc", "...") && required){
         if(splatedexist) this.token_error(this.S, "Unexpected token: splated argument can be only one.");
         if(type != name && type.name != "Array") this.token_error(this.S, "Unexpected token: splated argument must have `Array` type.");
+        required = false;
         this.next();
         argtype = "splated";
-    } else if(this.is("operator", "=")){
+    } else if(this.is("operator", "=") && required){
         this.next();
         defval = this.expression(false);
     } else if(this.is("punc",":")){
@@ -1331,6 +1339,7 @@ Cola.Parser.prototype.as_funcarg = function(splatedexist) {
     return new Cola.AST_ArgDef({
         name     : name,
         type     : name.type = (argtype == "splated" ? "Array" : type == name ? "dynamic" : type.name),
+        required : required,
         argtype  : argtype,
         defval   : defval,
         start    : type.start,

lib/std.js

@@ -121,12 +121,18 @@ Cola._ColaRuntime$$func_set_named_args = function _ColaRuntime$$func_set_named_a
     }
 }
 Cola._ColaRuntime$$func_set_named_args.i = 10;
-Cola._ColaRuntime$$arguments_def = { i : 11 };
+
+Cola._ColaRuntime$$error = function _ColaRuntime$$error(_error) {
+    throw new Error(_error);
+};
+Cola._ColaRuntime$$error.i = 11;
+
+Cola._ColaRuntime$$arguments_def = { i : 12 };
 
 Cola.$_cola = 
     Cola._ColaRuntime$$is + Cola._ColaRuntime$$isnt + Cola._ColaRuntime$$modulo + Cola._ColaRuntime$$isset + 
     Cola._ColaRuntime$$isntset + Cola._ColaRuntime$$clone + Cola._ColaRuntime$$array_last + Cola._ColaRuntime$$array_range + 
-    Cola._ColaRuntime$$array_asplice + Cola._ColaRuntime$$func_named_args + Cola._ColaRuntime$$func_set_named_args +
+    Cola._ColaRuntime$$array_asplice + Cola._ColaRuntime$$func_named_args + Cola._ColaRuntime$$func_set_named_args + Cola._ColaRuntime$$error +
     "var arguments;";
 
 Cola.Compressor.StdFuncs = {

lib/translate.js

@@ -1044,7 +1044,7 @@ Cola.AST_Toplevel.prototype.toJavaScript = function(options){
 
             node.argnames.forEach(function(val, i){
                 if(val.argtype == "positional"){
-                    if(val.defval instanceof Cola.AST_Noop && onfront) pos++, node.argnames[i] = val.name;
+                    if(val.defval instanceof Cola.AST_Noop && onfront && !val.required) pos++, node.argnames[i] = val.name;
                     else {
                         onfront = false;
                         delQueue.push(i);
@@ -1073,7 +1073,7 @@ Cola.AST_Toplevel.prototype.toJavaScript = function(options){
 
             posed.forEach(function(val, i){
                 var pos = val.pos; val = val.val;
-
+                console.log(val);
                 if(val.argtype == "splated"){
                     aftersplated = 0;
                     props.definitions.push(new Cola.AST_VarDef({
@@ -1086,12 +1086,20 @@ Cola.AST_Toplevel.prototype.toJavaScript = function(options){
                 }
                 else
 
-                if(val.defval instanceof Cola.AST_Noop) props.definitions.push(Cola.Constructions.PosedVarDef(val.name, val.type, pos, aftersplated++));
+                if(val.defval instanceof Cola.AST_Noop && !val.required) 
-                else props.definitions.push(Cola.Constructions.PosedWithDefsVarDef(val.name, val.type, val.defval, pos, aftersplated++));
+                    props.definitions.push(Cola.Constructions.PosedVarDef(val.name, val.type, pos, aftersplated++));
+                else if(val.defval instanceof Cola.AST_Noop && val.required){ 
+                    _ColaRuntime$$hash[Cola._ColaRuntime$$error.i] = true;
+                    props.definitions.push(Cola.Constructions.PosedWithDefsVarDef(val.name, val.type, new Cola.AST_Call({
+                        args       : [new Cola.AST_String({ value : "Argument `" + val.name.name + "` is required!" })],
+                        expression : new Cola.AST_SymbolRef({ name : '_ColaRuntime$$error' })
+                    }), pos, aftersplated++));
+                } else 
+                    props.definitions.push(Cola.Constructions.PosedWithDefsVarDef(val.name, val.type, val.defval, pos, aftersplated++));
             });
 
             named.forEach(function(val, i){
-                if(val.defval instanceof Cola.AST_Noop) props.definitions.push(new Cola.AST_VarDef({
+                if(val.defval instanceof Cola.AST_Noop && !val.required) props.definitions.push(new Cola.AST_VarDef({
                     type  : val.type,
                     name  : new Cola.AST_SymbolVar(val.name),
                     value : new Cola.AST_Dot({
@@ -1099,7 +1107,14 @@ Cola.AST_Toplevel.prototype.toJavaScript = function(options){
                         property   : val.name.name
                     })
                 })); 
-                else props.definitions.push(Cola.Constructions.NamedVarDef(val.name, val.type, val.defval, val.name.name));
+                else if(val.defval instanceof Cola.AST_Noop && val.required){
+                    _ColaRuntime$$hash[Cola._ColaRuntime$$error.i] = true;
+                    props.definitions.push(Cola.Constructions.NamedVarDef(val.name, val.type, new Cola.AST_Call({
+                        args       : [new Cola.AST_String({ value : "Argument `" + val.name.name + "` is required!" })],
+                        expression : new Cola.AST_SymbolRef({ name : '_ColaRuntime$$error' })
+                    }), val.name.name));
+                } else 
+                    props.definitions.push(Cola.Constructions.NamedVarDef(val.name, val.type, val.defval, val.name.name));
             });
 
             if(delQueue.length != 0 || named.length != 0) node.body.unshift(new Cola.AST_Var(props));