src/Util.hs

   1 -- |
   2 -- Module      : Util
   3 -- Copyright   : (c) 2008 Bertram Felgenhauer
   4 -- License     : BSD3
   5 --
   6 -- Maintainer  : Bertram Felgenhauer <int-e@gmx.de>
   7 -- Stability   : experimental
   8 -- Portability : portable
   9 --
  10 -- This module is part of Haskell PGMS.
  11 --
  12 -- Miscellaneous utility functions
  13 --
  14
  15 module Util (
  16     findFile,
  17     formatString
  18 ) where
  19
  20 import Paths_mine
  21
  22 import System.Directory
  23 import Data.Char
  24 import Data.List
  25
  26 -- find a data file
  27 -- this uses Paths_mine.getDataFileName, but also looks
  28 -- in a few other places for convenient in-place running.
  29 findFile :: FilePath -> IO FilePath
  30 findFile name = do
  31     let scan :: [IO FilePath] -> IO FilePath
  32         scan [] = error $ "Couldn't find file '" ++ name ++ "'"
  33         scan (c:cs) = do
  34             f <- c
  35             b <- doesFileExist f
  36             if b then return f else scan cs
  37     scan [getDataFileName name,
  38           return $ "data/" ++ name,
  39           return $ "../data/" ++ name,
  40           return $ name]
  41
  42 -- format a text string to fit nicely into 78 columns of text.
  43 formatString :: String -> String
  44 formatString = unlines . concatMap (block . (++" ")) . intersperse "" . lines
  45   where
  46     block "" = []
  47     block text = let
  48         (chunk, rest) = splitAt 78 text
  49         (end', start') = span (not . isSpace) (reverse chunk)
  50       in
  51         if null start' then chunk : block (dropWhile isSpace rest)
  52                        else reverse (dropWhile isSpace start')
  53                             : block (reverse end' ++ rest)