module Sound.Tidal.Utils where import Data.List (delete) mapBoth :: (a -> a) -> (a,a) -> (a,a) mapBoth f (a,b) = (f a, f b) mapPartTimes :: (a -> a) -> ((a,a),(a,a)) -> ((a,a),(a,a)) mapPartTimes f part = mapBoth (mapBoth f) part mapFst :: (a -> b) -> (a, c) -> (b, c) mapFst f (x,y) = (f x,y) mapSnd :: (a -> b) -> (c, a) -> (c, b) mapSnd f (x,y) = (x,f y) delta :: Num a => (a, a) -> a delta (a,b) = b-a -- | The midpoint of two values mid :: Fractional a => (a,a) -> a mid (a,b) = a + ((b - a) / 2) removeCommon :: Eq a => [a] -> [a] -> ([a],[a]) removeCommon [] bs = ([],bs) removeCommon as [] = (as,[]) removeCommon (a:as) bs | elem a bs = removeCommon as (delete a bs) | otherwise = (a:as',bs') where (as',bs') = removeCommon as bs readMaybe :: (Read a) => String -> Maybe a readMaybe s = case [x | (x,t) <- reads s, ("","") <- lex t] of [x] -> Just x _ -> Nothing {- | like `!!` selects @n@th element from xs, but wraps over at the end of @xs@ >>> map ((!!!) [1,3,5]) [0,1,2,3,4,5] [1,3,5,1,3,5] -} (!!!) :: [a] -> Int -> a (!!!) xs n = xs !! (n `mod` length xs) {- | Safer version of !! --} nth :: Int -> [a] -> Maybe a nth _ [] = Nothing nth 0 (x : _) = Just x nth n (_ : xs) = nth (n - 1) xs accumulate :: Num t => [t] -> [t] accumulate = accumulate' 0 where accumulate' _ [] = [] accumulate' n (a:xs) = (n+a):(accumulate' (n+a) xs) {- | enumerate a list of things >>> enumerate ["foo","bar","baz"] [(1,"foo"), (2,"bar"), (3,"baz")] -} enumerate :: [a] -> [(Int, a)] enumerate = zip [0..] {- | split given list of @a@ by given single a, e.g. >>> wordsBy (== ':') "bd:3" ["bd", "3"] -} wordsBy :: (a -> Bool) -> [a] -> [[a]] wordsBy p s = case dropWhile p s of [] -> [] s':rest -> (s':w) : wordsBy p (drop 1 s'') where (w, s'') = break p rest