Documentation

type restricted version of over

A LensRules used by makeClassy_'.

Make lenses and traversals for a type, and create a class when the type has no arguments. Works the same as makeClassy_ except that the resulting *classy* lens is also prefixed with an underscore.

A LensRules used by makeLenses_.

Build lenses (and traversals) with a sensible default configuration. Works the same as makeLenses except that the resulting lens is also prefixed with an underscore.

e.g.

data FooBar
  = Foo { x, y :: Int }
  | Bar { x :: Int }
makeLenses ''FooBar

will create

_x :: Lens' FooBar Int
_x f (Foo a b) = (\a' -> Foo a' b) <$> f a
_x f (Bar a)   = Bar <$> f a
_y :: Traversal' FooBar Int
_y f (Foo a b) = (\b' -> Foo a  b') <$> f b
_y _ c@(Bar _) = pure c

makeLenses_ = makeLensesWith lensRules_