Database.Relational.Query.Pi.Unsafe

This module defines typed projection path objects. Contains internal structure and unsafe 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.

width :: Pi r a -> Int

Get record width.

(<.>) :: Pi a b -> Pi b c -> Pi a c infixl 8

Compose projection path.

(<?.>) :: Pi a (Maybe b) -> Pi b c -> Pi a (Maybe c) infixl 8

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

(<?.?>) :: Pi a (Maybe b) -> Pi b (Maybe c) -> Pi a (Maybe c) infixl 8

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

pi :: [a] -> Pi r0 r1 -> [a]

Unsafely project untyped value list.

definePi

Arguments

:: PersistableWidth r1

=> Int

Index of flat SQL value list

-> Pi r0 r1

Result projection path

Unsafely define projection path from type r0 into type r1. Use infered PersistableRecordWidth.

defineDirectPi'

Arguments

:: PersistableRecordWidth r1

-> [Int]

Indexes of flat SQL value list

-> Pi r0 r1

Result projection path

Unsafely define projection path from type r0 into type r1.

defineDirectPi

Arguments

:: PersistableWidth r1

=> [Int]

Indexes of flat SQL value list

-> Pi r0 r1

Result projection path

Unsafely define projection path from type r0 into type r1. Use infered PersistableRecordWidth.

unsafeExpandIndexes :: Pi a b -> [Int]

Unsafely untype key to expand indexes.