小编Ray*_*Law的帖子

我的模块语法有问题.基本上我正在尝试将我的代码分成两个单独的文件,一个用于我正在创建的对象(AST),一个用于我的所有函数.

    --main.hs
    data AST = Add (AST) (AST)|
               Sub  (AST) (AST)|
               Mult (AST) (AST)|
               Ident Char|
               Num Int
               deriving Show

    aSTLeft (Num    l   ) = (Num l)
    aSTLeft (Ident  l   ) = (Ident l)
    aSTLeft (Add  l _   ) = l
    aSTLeft (Sub  l _   ) = l
    aSTLeft (Mult l _   ) = l
    aSTRight    (Num    r   ) = (Num r)
    aSTRight    (Ident  r   ) = (Ident r)
    aSTRight    (Add  _ r   ) = r
    aSTRight    (Sub  _ r …