gistfile1.txt

$ cat scriptedmain.hs
#!/usr/bin/env runhaskell

module ScriptedMain where

meaningOfLife :: Int
meaningOfLife = 42

main :: IO ()
main = putStrLn $ "Main: The meaning of life is " ++ show meaningOfLife
$ cat test.hs
#!/usr/bin/env runhaskell

module Test where

import ScriptedMain hiding (main)

main :: IO ()
main = putStrLn $ "Test: The meaning of life is " ++ show meaningOfLife
$ ghc -o scriptedmain -main-is ScriptedMain scriptedmain.hs
$ ./scriptedmain
Main: The meaning of life is 42
$ ghc -o test -main-is Test test.hs scriptedmain.hs
compilation IS NOT required
compilation IS NOT required
ld: duplicate symbol _ZCMain_main_info in scriptedmain.o and test.o
collect2: ld returned 1 exit status