Also, should i initalise automatically a new identifier when it appears in an expression? ml a doesn't appear before (add(1, 2) call(1, a))

Hello, How am I supposed to treat new identifiers? As mentioned, a new identifier doesn't need to be initialised explicitly, however, at the same time, the variable will be invisible out of the function area. So should I treat a as a new variabl...

Do I need to consider the possible mismatched brackets? Like text func((1 2, foo) Am I supposed to use d or f according to the different return values of the expression? And what is the maximum recursive depth of the expression? t...

Do we need to support a syntax like this? text x -x 2 x --1 Or only with legal in space-between text x - x 2 x - -1