SeqHelper.hs

-------------------------------------------------------------------
-- |
-- Module       : Data.Geospatial.Internal.SeqHelpers
-- Copyright    : (C) 2014-2018 HS-GeoJSON Project
-- License      : BSD-style (see the file LICENSE.md)
-- Maintainer   : Andrew Newman
-------------------------------------------------------------------
module Data.SeqHelper (
  sequenceHead
  , sequenceTail
  , unique
  ) where

import qualified Data.Sequence as Sequence

-- All but the last
sequenceHead :: Sequence.Seq a -> Sequence.Seq a
sequenceHead (headS Sequence.:|> _) = headS
sequenceHead _                      = Sequence.empty
{-# INLINE sequenceHead #-}

-- All but the first
sequenceTail :: Sequence.Seq a -> Sequence.Seq a
sequenceTail (_ Sequence.:<| tailS) = tailS
sequenceTail _                      = Sequence.empty
{-# INLINE sequenceTail #-}

unique :: Eq a => Sequence.Seq a -> Sequence.Seq a
unique Sequence.Empty      = Sequence.empty
unique (x Sequence.:<| xs) = (Sequence.<|) x (unique (Sequence.filter (x /=) xs))