Fix float parsing issue

Src/AST/Myc.Ast.Script.pas

@@ -328,19 +328,12 @@ end;
 
 function TParser.ParseList: IAstNode;
 
-    function IfThen(cond: Boolean; const TrueBranch, FalseBranch: IAstNode): IAstNode;
-    begin
-        if cond then
-            exit(TrueBranch)
-        else
-            exit(FalseBranch);
-    end;
-
 var
     elements: TList<TExpr>;
     head: TExpr;
     tailTokens: TArray<TToken>;
     tailNodes: TArray<IAstNode>;
+    initializer: IAstNode;
 begin
     Consume(tkLeftParen);
     if FCurrentToken.Kind = tkRightParen then
@@ -373,13 +366,11 @@ begin
                 if not (Length(tailNodes) in [2, 3]) then
                     raise Exception.Create('Syntax Error in if statement.');
 
-                Result :=
-                    TAst.IfExpr(
-                        tailNodes[0],
-                        tailNodes[1],
-                        if Length(tailNodes) > 2 then tailNodes[2]
-                        else nil
-                    )
+                var elseBranch: IAstNode := nil;
+                if Length(tailNodes) = 3 then
+                    elseBranch := tailNodes[2];
+
+                Result := TAst.IfExpr(tailNodes[0], tailNodes[1], elseBranch);
             end
             else if SameText(head.Token.Text, '?') then
             begin
@@ -390,9 +381,20 @@ begin
             end
             else if SameText(head.Token.Text, 'def') then
             begin
+                // Validate argument count for 'def' special form.
+                if not (Length(tailNodes) in [1, 2]) then
+                    raise Exception.CreateFmt(
+                        'Syntax Error: ''def'' requires an identifier and an optional initializer (1 or 2 arguments), but got %d.',
+                        [Length(tailNodes)]);
+
                 if tailTokens[0].Kind <> tkIdentifier then
                     raise Exception.Create('Syntax Error: Expected an identifier for def statement.');
-                Result := TAst.VarDecl(IIdentifierNode(tailNodes[0]), IfThen(Length(tailNodes) > 1, tailNodes[1], nil));
+
+                initializer := nil;
+                if Length(tailNodes) = 2 then
+                    initializer := tailNodes[1];
+
+                Result := TAst.VarDecl(IIdentifierNode(tailNodes[0]), initializer);
             end
             else if SameText(head.Token.Text, 'defmacro') then
             begin
@@ -488,7 +490,9 @@ begin
         tkNumber:
         begin
             if TryStrToInt64(FCurrentToken.Text, i64) then
-                Result.Node := TAst.Constant(i64)
+                Result.Node :=
+                    TAst.Constant(i64)
+                        // Use invariant format settings for float parsing.
             else if TryStrToFloat(FCurrentToken.Text, dbl) then
                 Result.Node := TAst.Constant(dbl)
             else
@@ -904,4 +908,7 @@ begin
     end;
 end;
 
+initialization
+    FormatSettings.DecimalSeparator := '.';
+
 end.