Haskell ...解析模块上的错误

Question

这可能有什么问题？我已经尝试了多种解决方案,但最终都会出现'模块'上的错误以及主要后面的=符号.有没有搞错？!？!？!

printTabuleiro :: [[Char]] -> IO()
printTabuleiro [] = []
printTabuleiro (l :lt) = putStr l : printTabuleiro lt

module Main where

main = let 
          a = ["#####\n","###o##\n"] 
       in do printTabuleiro a

现在我得到了这个编译错误,我不明白这里的类型匹配问题.顺便说一句,我是相当新的,不习惯功能,请不要把我加入火星.

[1 of 1] Compiling Main             ( visualisacao.hs, interpreted )

visualisacao.hs:14:27:
    Couldn't match expected type ‘IO ()’ with actual type ‘[IO ()]’
    In the expression: putStr l : printTabuleiro lt
    In an equation for ‘printTabuleiro’:
        printTabuleiro (l : lt) = putStr l : printTabuleiro lt

visualisacao.hs:14:38:
    Couldn't match expected type ‘[IO ()]’ with actual type ‘IO ()’
    In the second argument of ‘(:)’, namely ‘printTabuleiro lt’
    In the expression: putStr l : printTabuleiro lt
Failed, modules loaded: none.

Answer 1

您需要先声明您的模块.然后你需要声明你的导入.然后你可以定义你的功能.

Answer 2

该module声明只能通过评论和编译器编译指示类似语言扩展之前.将该module Main where行放在文件的顶部以及其下方的所有其他内容中.模块声明和任何函数或类型声明之间也必须有导入,所以它应该是这样的

module Main where

import Data.Char
import ...

printTabuleiro :: ...
printTabuleiro [] = ...

main = let
         a = ...
    in do printTabuleiro a