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{-# LANGUAGE LinearTypes #-}
{-# LANGUAGE NoImplicitPrelude, ScopedTypeVariables, BangPatterns, RankNTypes #-}
{-
This is a simplified version of Data.OldList module from base.
This caused an assertion failure in earlier version of linear
types implementation.
-}
module Data.OldList where
import GHC.Base
sortBy :: forall a . (a -> a -> Ordering) -> [a]
sortBy cmp = []
where
sequences (a:b:xs)
| a `cmp` b == GT = descending b [a] xs
| otherwise = ascending b (a:) xs
sequences xs = [xs]
-- descending :: a -> [a] -> [a] -> [[a]]
descending a as (b:bs)
| a `cmp` b == GT = descending b (a:as) bs
descending a as bs = (a:as): sequences bs
ascending :: a -> (forall i . [a] %i -> [a]) -> [a] -> [[a]]
ascending a as (b:bs)
| a `cmp` b /= GT = ascending b foo bs
where
foo :: [a] %k -> [a]
foo ys = as (a:ys)
ascending a as bs = let !x = as [a]
in x : sequences bs
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