{-# LANGUAGE TemplateHaskell, KindSignatures, PolyKinds, TypeOperators,
             DataKinds, ScopedTypeVariables, TypeFamilies, GADTs,
             UndecidableInstances #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  Data.Promotion.Prelude.Base
-- Copyright   :  (C) 2014 Jan Stolarek
-- License     :  BSD-style (see LICENSE)
-- Maintainer  :  Jan Stolarek (jan.stolarek@p.lodz.pl)
-- Stability   :  experimental
-- Portability :  non-portable
--
-- Implements promoted functions from GHC.Base module.
--
-- Because many of these definitions are produced by Template Haskell,
-- it is not possible to create proper Haddock documentation. Please look
-- up the corresponding operation in @Prelude@. Also, please excuse
-- the apparent repeated variable names. This is due to an interaction
-- between Template Haskell and Haddock.
--
----------------------------------------------------------------------------

module Data.Promotion.Prelude.Base (
  -- * Promoted functions from @GHC.Base@
  Foldr, Map, (:++), Otherwise, Id, Const, (:.), type ($), type ($!),
  Flip, Until, AsTypeOf, Seq,

  -- * Defunctionalization symbols
  FoldrSym0, FoldrSym1, FoldrSym2, FoldrSym3,
  MapSym0, MapSym1, MapSym2,
  (:++$), (:++$$), (:++$$$),
  OtherwiseSym0,
  IdSym0, IdSym1,
  ConstSym0, ConstSym1, ConstSym2,
  (:.$), (:.$$), (:.$$$), (:.$$$$),
  type ($$), type ($$$), type ($$$$),
  type ($!$), type ($!$$), type ($!$$$),
  FlipSym0, FlipSym1, FlipSym2, FlipSym3,
  UntilSym0, UntilSym1, UntilSym2, UntilSym3,
  AsTypeOfSym0, AsTypeOfSym1, AsTypeOfSym2,
  SeqSym0, SeqSym1, SeqSym2
  ) where

import Data.Singletons.TH
import Data.Singletons.Prelude.Base

$(promoteOnly [d|
  -- Does not singletoznize. See #30
  until                   :: (a -> Bool) -> (a -> a) -> a -> a
  until p f = go
    where
      go x | p x          = x
           | otherwise    = go (f x)
 |])
