Control.Arrow.Writer.Class

Documentation

class Arrow r => ArrowWriter w r | r -> w where

Methods

tell :: r w ()

look :: r a (a, w)

censor :: (w -> w) -> r a b -> r a b

Instances

(Monoid w, Arrow r) => ArrowWriter w (WriterT w r)

looksA :: ArrowWriter w r => r w b -> r a (a, b)

looks :: ArrowWriter w r => (w -> b) -> r a (a, b)