Data.Vinyl.Upcast

Documentation

class Overwrite xs ys where

Overwrite a wider record with a narrower record.

Methods

overwrite :: Rec el f xs -> Rec el f ys -> Rec el f xs

Instances

Overwrite k xs ([] k)

(IElem k y xs, Overwrite k xs ys) => Overwrite k xs ((:) k y ys)

slice :: (Functor f, Overwrite xs ys, xs <: ys) => (Rec el g ys -> f (Rec el g ys)) -> Rec el g xs -> f (Rec el g xs)

A lens from a record to a portion of it.

class (Overwrite ys xs, ys <: xs) => xs :> ys where

Upward record casting.

Methods

upcast :: Monoid (AltRec el f ys) => Rec el f xs -> Rec el f ys

Instances

(Overwrite k ys xs, (<:) k ys xs) => (:>) k xs ys

newtype AltRec el f rs

Wrapper for Rec with a different Monoid instance. Instead of lifting mappend, it acts on (f (el $ r)) directly, to support temporarily turning records into monoids by changing functors.

Constructors

AltRec

Fields

getRec :: Rec el f rs

Instances

(Monoid (f (($) * k el r)), Monoid (AltRec k el f rs)) => Monoid (AltRec k el f ((:) k r rs))

Monoid (AltRec k el f ([] k))