Database.Relational.Query.Pi

This module defines typed projection path objects. Contains normal interfaces.

Projection path

data Pi r0 r1

Projection path from type r0 into type r1. This type also indicate key object which type is r1 for record type r0.

Instances

ProjectableApplicative (Pi a)

Compose projection path Pi which has record result type using applicative style.

ProjectableFunctor (Pi a)

Compose seed of projection path Pi which has record result type.

pfmap :: ProductConstructor (a -> b) => (a -> b) -> Pi r a -> Pi r b

Projectable fmap of Pi type.

pap :: Pi r (a -> b) -> Pi r a -> Pi r b

Projectable ap of Pi type.

(<.>) :: Pi a b -> Pi b c -> Pi a c

Compose projection path.

(<?.>) :: Pi a (Maybe b) -> Pi b c -> Pi a (Maybe c)

Compose projection path. Maybe phantom functor is map-ed.

(<?.?>) :: Pi a (Maybe b) -> Pi b (Maybe c) -> Pi a (Maybe c)

Compose projection path. Maybe phantom functors are join-ed like >=>.

id' :: PersistableWidth a => Pi a a

Identity projection path.

fst'

Arguments

:: PersistableWidth a

=> Pi (a, b) a

Projection path of fst.

Projection path for fst of tuple.

snd'

Arguments

:: (PersistableWidth a, PersistableWidth b)

=> Pi (a, b) b

Projection path of snd.

Projection path for snd of tuple.