Separator.hs

{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE DeriveGeneric #-}

{-|
Module      : Data.Svfactor.Text.Space
Copyright   : (C) CSIRO 2017-2018
License     : BSD3
Maintainer  : George Wilson <george.wilson@data61.csiro.au>
Stability   : experimental
Portability : non-portable

A sum type for space characters
-}

module Data.Svfactor.Text.Separator
  ( Separator
  , HasSeparator (..)
  , comma, pipe, tab
  )
where

import Control.Lens (Lens')

-- | By what are your values separated? The answer is often 'comma', but not always.
--
-- A 'Separator' is just a 'Char'. It could be a sum type instead, since it
-- will usually be comma or pipe, but our preference has been to be open here
-- so that you can use whatever you'd like. There are test cases, for example,
-- ensuring that you're free to use null-byte separated values if you so desire.
type Separator = Char

-- | Classy lens for 'Separator'
class HasSeparator c where
  separator :: Lens' c Separator

instance HasSeparator Char where
  separator = id
  {-# INLINE separator #-}

-- | The venerable comma separator. Used for CSV documents.
comma :: Separator
comma = ','

-- | The pipe separator. Used for PSV documents.
pipe :: Separator
pipe = '|'

-- | Tab is a separator too - why not?
tab :: Separator
tab = '\t'