utility-ht-0.0.11: Various small helper functions for Lists, Maybes, Tuples, Functions

Data.Tuple.HT

Contents

Synopsis

• mapPair :: (a -> c, b -> d) -> (a, b) -> (c, d)
• mapFst :: (a -> c) -> (a, b) -> (c, b)
• mapSnd :: (b -> c) -> (a, b) -> (a, c)
• swap :: (a, b) -> (b, a)
• forcePair :: (a, b) -> (a, b)
• fst3 :: (a, b, c) -> a
• snd3 :: (a, b, c) -> b
• thd3 :: (a, b, c) -> c
• mapTriple :: (a -> d, b -> e, c -> f) -> (a, b, c) -> (d, e, f)
• mapFst3 :: (a -> d) -> (a, b, c) -> (d, b, c)
• mapSnd3 :: (b -> d) -> (a, b, c) -> (a, d, c)
• mapThd3 :: (c -> d) -> (a, b, c) -> (a, b, d)
• curry3 :: ((a, b, c) -> d) -> a -> b -> c -> d
• uncurry3 :: (a -> b -> c -> d) -> (a, b, c) -> d

# Pair

mapPair :: (a -> c, b -> d) -> (a, b) -> (c, d) Source

Cf. '(Control.Arrow.***)'.

Apply two functions on corresponding values in a pair, where the pattern match on the pair constructor is lazy. This is crucial in recursions such as the one of `partition`. One the other hand there are applications where strict application is crucial, e.g. `mapSnd f ab` where the left pair member is a large lazy list. With the lazy `mapSnd` we make the application of `f` depend on the whole pair `ab`. See Data.Tuple.Example for two examples where one variant is definitely better than the other one.

mapFst :: (a -> c) -> (a, b) -> (c, b) Source

`first`

mapSnd :: (b -> c) -> (a, b) -> (a, c) Source

`second`

swap :: (a, b) -> (b, a) Source

forcePair :: (a, b) -> (a, b) Source

# Triple

fst3 :: (a, b, c) -> a Source

snd3 :: (a, b, c) -> b Source

thd3 :: (a, b, c) -> c Source

mapTriple :: (a -> d, b -> e, c -> f) -> (a, b, c) -> (d, e, f) Source

mapFst3 :: (a -> d) -> (a, b, c) -> (d, b, c) Source

mapSnd3 :: (b -> d) -> (a, b, c) -> (a, d, c) Source

mapThd3 :: (c -> d) -> (a, b, c) -> (a, b, d) Source

curry3 :: ((a, b, c) -> d) -> a -> b -> c -> d Source

uncurry3 :: (a -> b -> c -> d) -> (a, b, c) -> d Source