Haskell...模块解析错误

Question

这有什么问题吗？我尝试了多种解决方案，但最终都以 'module' 和 main 之后的 = 符号中的错误告终。到底是什么？！？！？！

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，不习惯功能请不要将我推向火星。

[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

module 声明只能在注释和编译器编译指示（如语言扩展）之前。将 module Main where 行放在文件的顶部，其他所有内容都放在它下面。导入还必须位于模块声明和任何函数或类型声明之间，因此它应该看起来像

module Main where

import Data.Char
import ...

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

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

Answer 2

您需要先声明您的模块。然后你需要申报你的进口。然后你可以定义你的功能。

Answer 3

IIRC，我的问题是缩进不当（严重！）确保您使用的是三个空格而不是 TAB，并确保正确地缩进

Haskell...模块解析错误

Haskell... parse error on module

haskell

main

module