Data.Lazify

Record types in Haskell can be made lazy through lazy pattern matching. This module offers functions for making them lazy generically.

Documentation

class Lazifiable a where

A class for types that can be lazified. A generic default is provided for convenience. To lazify a type using its generic representation, use genericLazify.

Minimal complete definition

Nothing

Methods

lazify :: a -> a

Lazily rewrap a record. Applying lazify to a record and then pattern matching on it strictly is equivalent to pattern matching on it lazily.

strictFirst :: (a -> a') -> (a, b) -> (a', b)
strictFirst f (a, b) = (f a, b)

lazyFirst :: (a -> a') -> (a, b) -> (a', b)
lazyFirst f = strictFirst f . lazify
-- Equivalently
lazyFirst f ~(a, b) = (f a, b)

default lazify :: (Generic a, GLazifiable a (Rep a)) => a -> a

Instances

Lazifiable ()

Defined in Data.Lazify.Internal

Methods

lazify :: () -> ()

Lazifiable a => Lazifiable (Min a)

Defined in Data.Lazify.Internal

Methods

lazify :: Min a -> Min a

Lazifiable a => Lazifiable (Max a)

Defined in Data.Lazify.Internal

Methods

lazify :: Max a -> Max a

Lazifiable a => Lazifiable (First a)

Defined in Data.Lazify.Internal

Methods

lazify :: First a -> First a

Lazifiable a => Lazifiable (Last a)

Defined in Data.Lazify.Internal

Methods

lazify :: Last a -> Last a

Lazifiable a => Lazifiable (WrappedMonoid a)

Defined in Data.Lazify.Internal

Methods

lazify :: WrappedMonoid a -> WrappedMonoid a

Lazifiable a => Lazifiable (Identity a)

Defined in Data.Lazify.Internal

Methods

lazify :: Identity a -> Identity a

Lazifiable a => Lazifiable (Dual a)

Defined in Data.Lazify.Internal

Methods

lazify :: Dual a -> Dual a

Lazifiable a => Lazifiable (Sum a)

Defined in Data.Lazify.Internal

Methods

lazify :: Sum a -> Sum a

Lazifiable a => Lazifiable (Product a)

Defined in Data.Lazify.Internal

Methods

lazify :: Product a -> Product a

Lazifiable (NonEmpty a)

Defined in Data.Lazify.Internal

Methods

lazify :: NonEmpty a -> NonEmpty a

Lazifiable (Tree a)

Defined in Data.Lazify.Internal

Methods

lazify :: Tree a -> Tree a

Typeable a => Lazifiable (TypeRep a)

Defined in Data.Lazify.Internal

Methods

lazify :: TypeRep a -> TypeRep a

Lazifiable (a, b)

Defined in Data.Lazify.Internal

Methods

lazify :: (a, b) -> (a, b)

Lazifiable (Arg a b)

Defined in Data.Lazify.Internal

Methods

lazify :: Arg a b -> Arg a b

Lazifiable (Proxy a)

Defined in Data.Lazify.Internal

Methods

lazify :: Proxy a -> Proxy a

Lazifiable (a, b, c)

Defined in Data.Lazify.Internal

Methods

lazify :: (a, b, c) -> (a, b, c)

Lazifiable a => Lazifiable (Const a b)

Defined in Data.Lazify.Internal

Methods

lazify :: Const a b -> Const a b

Lazifiable (f a) => Lazifiable (Ap f a)

Defined in Data.Lazify.Internal

Methods

lazify :: Ap f a -> Ap f a

Lazifiable (f a) => Lazifiable (Alt f a)

Defined in Data.Lazify.Internal

Methods

lazify :: Alt f a -> Alt f a

Coercible a b => Lazifiable (Coercion a b)

Defined in Data.Lazify.Internal

Methods

lazify :: Coercion a b -> Coercion a b

a ~ b => Lazifiable (a :~: b)

Defined in Data.Lazify.Internal

Methods

lazify :: (a :~: b) -> a :~: b

Lazifiable b => Lazifiable (Tagged a b)

Defined in Data.Lazify.Internal

Methods

lazify :: Tagged a b -> Tagged a b

Lazifiable (t a) => Lazifiable (Reverse t a)

Defined in Data.Lazify.Internal

Methods

lazify :: Reverse t a -> Reverse t a

Lazifiable (f a) => Lazifiable (IdentityT f a)

Defined in Data.Lazify.Internal

Methods

lazify :: IdentityT f a -> IdentityT f a

Lazifiable (f a) => Lazifiable (Backwards f a)

Defined in Data.Lazify.Internal

Methods

lazify :: Backwards f a -> Backwards f a

Lazifiable (a, b, c, d)

Defined in Data.Lazify.Internal

Methods

lazify :: (a, b, c, d) -> (a, b, c, d)

Lazifiable (Product f g a)

Defined in Data.Lazify.Internal

Methods

lazify :: Product f g a -> Product f g a

a ~~ b => Lazifiable (a :~~: b)

Defined in Data.Lazify.Internal

Methods

lazify :: (a :~~: b) -> a :~~: b

Lazifiable (f (g a)) => Lazifiable ((f :.: g) a)

Defined in Data.Lazify.Internal

Methods

lazify :: (f :.: g) a -> (f :.: g) a

Lazifiable (a, b, c, d, e)

Defined in Data.Lazify.Internal

Methods

lazify :: (a, b, c, d, e) -> (a, b, c, d, e)

Lazifiable (f (g a)) => Lazifiable (Compose f g a)

Defined in Data.Lazify.Internal

Methods

lazify :: Compose f g a -> Compose f g a

Lazifiable (a, b, c, d, e, f)

Defined in Data.Lazify.Internal

Methods

lazify :: (a, b, c, d, e, f) -> (a, b, c, d, e, f)

Lazifiable (a, b, c, d, e, f, g)

Defined in Data.Lazify.Internal

Methods

lazify :: (a, b, c, d, e, f, g) -> (a, b, c, d, e, f, g)

Lazifiable (a, b, c, d, e, f, g, h)

Defined in Data.Lazify.Internal

Methods

lazify :: (a, b, c, d, e, f, g, h) -> (a, b, c, d, e, f, g, h)

Lazifiable (a, b, c, d, e, f, g, h, i)

Defined in Data.Lazify.Internal

Methods

lazify :: (a, b, c, d, e, f, g, h, i) -> (a, b, c, d, e, f, g, h, i)

Lazifiable (a, b, c, d, e, f, g, h, i, j)

Defined in Data.Lazify.Internal

Methods

lazify :: (a, b, c, d, e, f, g, h, i, j) -> (a, b, c, d, e, f, g, h, i, j)

genericLazify :: forall a. (Generic a, GLazifiable a (Rep a)) => a -> a

Lazify a record using its generic representation.

Note that newtypes are treated specially: a newtype is lazified by lazifying its underlying type using its Lazifiable instance.

($~) :: forall rep a (b :: TYPE rep). Lazifiable a => (a -> b) -> a -> b

Apply a function to a lazified value.

Note to users of TypeApplications: For GHC >= 9.0.1, the representation is marked as inferred. Before that, doing so is impossible and the representation must be passed as the first type argument. I'm sorry.