...

compiler/NubLang/Syntax/Tokenizer.cs

@@ -56,6 +56,7 @@ public sealed class Tokenizer
         [['%']] = Symbol.Percent,
         [['|']] = Symbol.Pipe,
         [['@']] = Symbol.At,
+        [['?']] = Symbol.QuestionMark,
     };
 
     private static readonly (char[] Pattern, Symbol Symbol)[] OrderedSymbols = Symbols