-----------------------------------------------------------------------------
-- |
-- Module      :  Data.Semigroup
-- Copyright   :  (c) 2020-2021 EMQ Technologies Co., Ltd.
-- License     :  BSD-style (see the LICENSE file)
--
-- Maintainer  :  Feng Lee, feng@emqx.io
--                Yang M, yangm@emqx.io
-- Stability   :  experimental
-- Portability :  portable
--
-- The Semigroup typeclass.
--
-----------------------------------------------------------------------------
module Data.Semigroup
  ( class Semigroup
  , append, (<>)
  ) where

import Data.Unit (Unit, unit)

class Semigroup a where
  append :: a -> a -> a

infixr 5 append as <>

instance Semigroup (List a) where
  append = listAppend

instance Semigroup Unit where
  append _ _ = unit

instance (Semigroup a, Semigroup b) => Semigroup (a, b) where
  append (a1, b1) (a2, b2) = (a1 <> a2, b1 <> b2)

-- | Append two Strings
foreign import stringAppend :: String -> String -> String

-- | Append two Lists
foreign import listAppend :: forall a. List a -> List a -> List a