Relude.Extra.Foldable

Contains utility functions for working with tuples.

Since: 0.6.0.0

Documentation

foldlSC :: forall t b a. Foldable t => (b -> a -> Either b b) -> b -> t a -> b

A left-associative fold that's tail-recursive but can still short-circuit. Returning a Left short-circuits and immediately returns the value inside. Returning a Right continues the fold as usual with the value inside.

>>> foldlSC (\acc x -> if x == 0 then Left 0 else Right $! acc * x) 1 [1..6]
720
>>> foldlSC (\acc x -> if x == 0 then Left 0 else Right $! acc * x) 1 (0:error "Short-circuiting should keep this from happening")
0

Since: 0.6.0.0

average :: forall a f. (Foldable f, Fractional a) => f a -> Maybe a

Given a Foldable of Fractional elements, computes the average if possible and returns Maybe element.

>>> average [42]
Just 42.0
>>> average @Double [1, 2, 3, 4]
Just 2.5
>>> average @Float [1.5, 2.5, 3 ,4]
Just 2.75
>>> average []
Nothing

Since: 1.0.0.0