Question

I’m trying to compile the following code with GHC:

module Test where

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

null = ()

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

If I just run ghc Test.hs, I get:

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

So I try ghc -package haskell98 Test.hs:

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

It doesn’t seem right, but I try 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'.

So then I try 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

How do I compile this code? I’m using GHC 7.4.1.

Answer 1

Import Data.Maybe. The haskell98 package is no longer compatible with base, so using the haskell98 modules brings just unnecessary pain.