功能通用于Foldable和Data.Vector.Unboxed

Question

Data.Vector.Unboxed is not an instance of Foldable . What is the best way to write a function which works on instances of Foldable as well as on unboxed vectors? For example this version of sum works with lists and boxed vectors, but not unboxed:

sum :: (Foldable t, Num a) => t a -> a
sum = Foldable.foldl' (+) 0

Answer 1

This sounds like something mono-traversable could do for you. Fe it already contains a sum variant:

osum :: (MonoFoldable mono, Num (Element mono)) => mono -> Element mono
osum = ofoldl' (+) 0