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{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
-- | Utility functions for reading cabal file fields through template haskell.
module Distribution.PackageDescription.TH (
-- * Template Haskell functions
packageVariable,
packageVariableFrom,
-- * Cabal file data structures
-- | The data structures for the cabal file are re-exported here for ease of use.
PackageDescription(..),
PackageIdentifier(..),
Version(..)
) where
import Distribution.PackageDescription
import Distribution.Package
import Distribution.Version
import Distribution.Text (Text, display)
import Distribution.Verbosity (silent)
import Distribution.PackageDescription.Parse (readPackageDescription)
import System.Directory (getCurrentDirectory, getDirectoryContents)
import Data.List (isSuffixOf)
import Language.Haskell.TH (Q, Exp, stringE, runIO)
-- | Renders the package variable specified by the function.
-- The cabal file interrogated is the first one that is found
-- in the current working directory.
packageVariable :: Text a => (PackageDescription -> a) -> Q Exp
packageVariable = renderField currentPackageDescription
-- | Renders the package variable specified by the function, from a cabal file
-- and the given path.
packageVariableFrom :: Text a => FilePath -> (PackageDescription -> a) -> Q Exp
packageVariableFrom s = renderField $ fmap packageDescription (readPackageDescription silent s)
------
renderField :: Text b => IO a -> (a -> b) -> Q Exp
renderField pd f = runIO pd >>= stringE . display . f
currentPackageDescription :: IO PackageDescription
currentPackageDescription = fmap packageDescription $ do
dir <- getCurrentDirectory
cs <- cabalFiles dir
case cs of
(c:_) -> readPackageDescription silent c
[] -> error $ "Couldn't find a cabal file in the current working directory (" ++ dir ++ ")"
cabalFiles :: FilePath -> IO [FilePath]
cabalFiles dir = do
files <- getDirectoryContents dir
return $ filter (".cabal" `isSuffixOf`) files
{-
Smart ways of getting the cabal file:
* Get this module name, use TH.location and loc_module. Parse each
cabal file in the cwd and look for references to this module
in each thing.
-}
|
