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module Util where
import Control.Monad
import System.Exit
fixpoint :: Eq a => (a -> a) -> a -> a
fixpoint f initVal =
let values = iterate f initVal
pairs = zip values (tail values)
in fst . head $ dropWhile (uncurry (/=)) pairs
tryEither :: Either String a -> IO a
tryEither (Left err) = die err
tryEither (Right x) = return x
tryEither' :: Show e => Either e a -> IO a
tryEither' (Left err) = die (show err)
tryEither' (Right x) = return x
fromRight :: Either a b -> b
fromRight (Right x) = x
fromRight (Left _) = error "fromRight on Left"
isRight :: Either a b -> Bool
isRight (Right _) = True
isRight (Left _) = False
while :: Monad m => a -> (a -> m (Maybe a)) -> m ()
while val f = f val >>= \case
Nothing -> return ()
Just val' -> while val' f
whenM :: Monad m => m Bool -> m a -> m ()
whenM b a = b >>= \b' -> if b' then void a else return ()
ifM :: Monad m => m Bool -> m a -> m a -> m a
ifM b t e = b >>= \b' -> if b' then t else e
splitOn :: Eq a => a -> [a] -> [[a]]
splitOn _ [] = [[]]
splitOn spl (x:xs)
| x == spl = [] : splitOn spl xs
| otherwise = let (r : rs) = splitOn spl xs in (x:r) : rs
|
