Packaging data files accessed from TemplateHaskell with Cabal.

HelloWorld.hs

-- A simpler alternative to http://www.alfredodinapoli.com/posts/2013-08-17-copy-your-project-resources-at-configure-time.html
-- See http://www.reddit.com/r/haskell/comments/1kjpop/copy_your_project_resources_at_configure_time/

module HelloWorld (helloWorld)
       where

import Language.Haskell.TH
import Language.Haskell.TH.Syntax (addDependentFile)
import System.FilePath

helloWorld :: Q Exp
helloWorld = do
  loc <- location
  let fileName = takeDirectory (loc_filename loc)
                 </> ".." </> "data" </> "test.txt"
  str <- runIO $ do
    -- We assume that the current module is in '<package_root>/src/'
    -- and the data file is in '<package_root>/data'.
    readFile fileName
  addDependentFile fileName
  litE . stringL $ str

Main.hs

{-# LANGUAGE TemplateHaskell #-}

module Main
       where

import HelloWorld (helloWorld)

main :: IO ()
main = putStrLn $(helloWorld)

test.txt

Hello, compile-time IO world!

th-extra-source-files.cabal

name:                th-extra-source-files
version:             0.1.0.0
-- synopsis:
-- description:
license:             GPL-3
license-file:        LICENSE
author:              Mikhail Glushenkov
maintainer:          mikhail.glushenkov@gmail.com
-- copyright:
category:            Testing
build-type:          Simple
extra-source-files:  data/test.txt
cabal-version:       >=1.10

executable th-extra-source-files
  main-is: Main.hs
  -- other-modules:
  other-extensions:    TemplateHaskell
  build-depends:       base >=4.5 && <5,
                       template-haskell, filepath
  hs-source-dirs:      src
  default-language:    Haskell2010