Literate setup script, and use -fasm. it's faster

Setup.lhs

@@ -0,0 +1,19 @@
+#!/usr/bin/env runhaskell
+> module Main where
+> import Distribution.Simple
+> import Distribution.Setup   ( ConfigFlags (..) )
+> import System.Directory     ( findExecutable )
+> 
+> main :: IO ()
+> main = defaultMainWithHooks (defaultUserHooks { postConf = defaultPostConf })
+>     where defaultPostConf args flags lbi {- xx -}
+>               = do args' <- fmap (args++) (configToArgs flags)
+>                    (postConf defaultUserHooks) args' flags lbi {- xx -}
+> 
+> configToArgs :: ConfigFlags -> IO [String]
+> configToArgs (ConfigFlags { configHcPath = Just hcPath })
+>     = do exec <- findExecutable hcPath
+>          case exec of
+>            Just realPath -> return ["--with-ghc="++realPath]
+>            Nothing -> return ["--with-ghc="++hcPath]
+> configToArgs _ = return []