cabal build のときに自動的に走る前処理だけを実行する

cabal-preprocess.hs

module Main where
import Control.Applicative ((<$>))
import Data.List (isSuffixOf)
import System.Exit (exitFailure)
import System.IO (hPutStrLn, stderr)
import System.Directory (getDirectoryContents)
import System.FilePath (takeDirectory, (</>))
import Distribution.Verbosity (silent)
import Distribution.PackageDescription.Parse (readPackageDescription)
import Distribution.PackageDescription.Configuration (flattenPackageDescription)
import Distribution.Simple.LocalBuildInfo (withComponentsLBI)
import Distribution.Simple.Configure (tryGetConfigStateFile, localBuildInfoFile)
import Distribution.Simple.Build (initialBuildSteps)
import Distribution.Simple.PreProcess (preprocessComponent, knownSuffixHandlers)

die :: String -> IO ()
die msg = do
  hPutStrLn stderr msg
  exitFailure

main :: IO ()
main = do
  files <- filter (".cabal" `isSuffixOf`) <$> getDirectoryContents "."
  case files of
    [] -> die "No cabal file found."
    file:_ -> doPreprocess file

doPreprocess :: FilePath -> IO ()
doPreprocess cabalPath = do
  pkgDesc <- flattenPackageDescription <$> readPackageDescription silent cabalPath
  elbi <- tryGetConfigStateFile $ localBuildInfoFile distDir
  case elbi of
    Left err -> die err
    Right lbi -> do
      initialBuildSteps distDir pkgDesc lbi silent
      withComponentsLBI pkgDesc lbi $ \comp _ -> do
        preprocessComponent pkgDesc comp lbi False silent knownSuffixHandlers
  where
    distDir = takeDirectory cabalPath </> "dist"