Util.hs

{-# LANGUAGE DisambiguateRecordFields, TypeFamilies,
    StandaloneDeriving, DeriveFunctor, DeriveFoldable, GeneralizedNewtypeDeriving #-}

-------------------------------------------------------------------------------------
-- |
-- Copyright   : (c) Hans Hoglund 2012
-- License     : BSD-style
-- Maintainer  : hans@hanshoglund.se
-- Stability   : experimental
-- Portability : GHC
--
-------------------------------------------------------------------------------------

module Language.Modulo.Util (
        -- ** String and Char stuff
        toUpperChar,
        toLowerChar,
        toUpperString,
        toLowerString,
        toCapitalString,

        -- ** List stuff
        withPrefix,
        withSuffix,
        sep,
        pre,
        post,
        wrap,
        concatSep,
        concatPre,
        concatPost,
        concatWrap,
        divideList,
        breakList,
        
        -- ** Monad stuff
        concatMapM
  ) where

import qualified Data.Char   as Char
import qualified Data.Monoid as Monoid
import qualified Data.List   as List

-------------------------------------------------------------------------------------
-- String and Char
-------------------------------------------------------------------------------------

-- | 
-- Synonym for 'Char.toUpper'
toUpperChar :: Char -> Char
toUpperChar = Char.toUpper

-- | 
-- Synonym for 'Char.toLower'
toLowerChar :: Char -> Char
toLowerChar = Char.toLower

-- | 
-- Synonym for 'fmap Char.toUpper'
toUpperString :: String -> String
toUpperString = fmap Char.toUpper

-- | 
-- Synonym for 'fmap Char.toLower'
toLowerString :: String -> String
toLowerString = fmap Char.toLower

-- | 
-- Convert a string to use upper case for the leading letter and lower case for 
-- remaining letters.
toCapitalString :: String -> String
toCapitalString [] = []
toCapitalString (x:xs) = toUpperChar x : toLowerString xs



-------------------------------------------------------------------------------------
-- List
-------------------------------------------------------------------------------------

-- | 
-- Synonym for '(++)'
--
withPrefix :: [a] -> [a] -> [a]
withPrefix x = (x ++)

-- | 
-- Synonym for 'flip (++)'
--
withSuffix :: [a] -> [a] -> [a]
withSuffix x = (++ x)

-- | 
-- Separate a list by the given element.
--
-- Equivalent to 'List.intersperse'
--
sep :: a -> [a] -> [a]
sep = List.intersperse

-- | 
-- Initiate and separate a list by the given element.
--
pre :: a -> [a] -> [a]
pre x = (x :) . sep x

-- | 
-- Separate and terminate a list by the given element.
--
post :: a -> [a] -> [a]
post x = withSuffix [x] . sep x

-- | 
-- Separate and terminate a list by the given element.
--
wrap :: a -> a -> [a] -> [a]
wrap x y = (x :) . withSuffix [y] . sep x

-- | 
-- Combination of 'concat' and 'sep'.
--
concatSep :: [a] -> [[a]] -> [a]
concatSep x = concat . sep x

-- | 
-- Combination of 'concat' and 'pre'.
--
concatPre :: [a] -> [[a]] -> [a]
concatPre x = concat . pre x

-- | 
-- Combination of 'concat' and 'post'.
--
concatPost :: [a] -> [[a]] -> [a]
concatPost x = concat . post x

-- | 
-- Combination of 'concat' and 'wrap'.
--
concatWrap :: [a] -> [a] -> [[a]] -> [a]
concatWrap x y = concat . wrap x y

-- | 
-- Divide a list into parts of maximum length n.
--
divideList :: Int -> [a] -> [[a]]
divideList n xs 
    | length xs <= n = [xs]
    | otherwise      = [take n xs] ++ (divideList n $ drop n xs)

-- | 
-- Break up a list into parts of maximum length n, inserting the given list as separator.
-- Useful for breaking up strings, as in @breakList 80 "\n" str@.
--
breakList :: Int -> [a] -> [a] -> [a]
breakList n z = Monoid.mconcat . List.intersperse z . divideList n    

-- | 
-- Break up a list into parts of maximum length n, inserting the given list as separator.
-- Useful for breaking up strings, as in @breakList 80 "\n" str@.
--
concatMapM :: (Monad f, Functor f) => (a -> f [b]) -> [a] -> f [b]
concatMapM f = fmap concat . mapM f