{-# language MagicHash #-}
{-# language UnboxedTuples #-}

module Compat
  ( unsafeShrinkAndFreeze
  , unsafeShrinkAndFreeze#
  ) where

import Control.Monad.ST (ST)
import Data.Primitive (SmallArray,SmallMutableArray)
import GHC.Exts (SmallArray#,SmallMutableArray#,Int#,State#)

import qualified Data.Primitive as PM
import qualified GHC.Exts as Exts

-- Shrink the mutable array in place and then freeze it.
-- The argument must not be reused after being passed to
-- this function.
unsafeShrinkAndFreeze ::
     SmallMutableArray s a
  -> Int
  -> ST s (SmallArray a)
{-# inline unsafeShrinkAndFreeze #-}
unsafeShrinkAndFreeze arr = PM.freezeSmallArray arr 0

unsafeShrinkAndFreeze# ::
     SmallMutableArray# s a
  -> Int#
  -> State# s
  -> (# State# s, SmallArray# a #)
{-# inline unsafeShrinkAndFreeze# #-}
unsafeShrinkAndFreeze# x n s0 =
  Exts.freezeSmallArray# x 0# n s0