import Development.Hake
import Development.Hake.FunSetRaw
import System.Process (readProcess)
import Text.RegexPR   (matchRegexPR)
import Data.Maybe     (fromJust)

main = do
  hake [

   dflt [ "a.out" ]
   ,
   file [ "a.out" ] [ "hello.c" ] $ const [ [ "cc", "hello.c" ] ]

   ]
  ret <- readProcess "file" [ "a.out" ] ""
  let ftype = fromJust $ lookup 1 $ snd $ fromJust $ matchRegexPR ".+:\\s+([^,]+)" ret
  hake [

   dflt [ "sys", "conv" ]
   ,
   task "sys" [ [ "true", "Building", "sys", "with", "file", "type", ftype ] ]
   ,
   task "conv" [ [ "true", "Building", "conv", "with", "file", "type", ftype ] ]

   ]