haskell - GHC 包冲突

Question

我正在尝试使用 GHC 编译以下代码:

module Test where

import Maybe
import Prelude hiding (null)
import System.IO

null = ()

main :: IO ()
main = putStrLn "Hello, world!"

如果我只是运行 ghc Test.hs ，我得到:

Could not find module `Maybe'
It is a member of the hidden package `haskell98-2.0.0.1'.

所以我试试 ghc -package haskell98 Test.hs :

Ambiguous module name `Prelude':
  it was found in multiple packages: base haskell98-2.0.0.1

好像不对，不过我试试 ghc -package haskell98 -hide-package base Test.hs :

Could not find module `System.IO'
It is a member of the hidden package `base'.
It is a member of the hidden package `haskell2010-1.1.0.1'.

那我试试 ghc -package haskell98 -hide-package base -package haskell2010 Test.hs :

Ambiguous module name `Prelude':
  it was found in multiple packages:
  haskell2010-1.1.0.1 haskell98-2.0.0.1

如何编译此代码？我正在使用 GHC 7.4.1。

Answer 1

进口 Data.Maybe . haskell98包不再兼容 base ，所以使用 haskell98模块只会带来不必要的痛苦。