Safe Haskell	Safe
Language	Haskell2010

HLRDB.Primitives.Aggregate

Description

Combinators that can be used for aggregating independent queries. See my article about aggregating mget queries for more information.

Synopsis

Documentation

newtype T x y a b Source #

Abstract representation for aggregation.

Constructors

T (Traversal a b x y)

Instances

Profunctor (T x y) Source #
Methods dimap :: (a -> b) -> (c -> d) -> T x y b c -> T x y a d # lmap :: (a -> b) -> T x y b c -> T x y a c # rmap :: (b -> c) -> T x y a b -> T x y a c # (#.) :: Coercible * c b => (b -> c) -> T x y a b -> T x y a c # (.#) :: Coercible * b a => T x y b c -> (a -> b) -> T x y a c #
Choice (T x y) Source #
Methods left' :: T x y a b -> T x y (Either a c) (Either b c) # right' :: T x y a b -> T x y (Either c a) (Either c b) #
Traversing (T x y) Source #
Methods traverse' :: Traversable f => T x y a b -> T x y (f a) (f b) # wander :: (forall (f :: * -> *). Applicative f => (a -> f b) -> s -> f t) -> T x y a b -> T x y s t #
Strong (T x y) Source #
Methods first' :: T x y a b -> T x y (a, c) (b, c) # second' :: T x y a b -> T x y (c, a) (c, b) #
Functor (T x y a) Source #
Methods fmap :: (a -> b) -> T x y a a -> T x y a b # (<$) :: a -> T x y a b -> T x y a a #
Applicative (T x y a) Source #
Methods pure :: a -> T x y a a # (<>) :: T x y a (a -> b) -> T x y a a -> T x y a b # liftA2 :: (a -> b -> c) -> T x y a a -> T x y a b -> T x y a c # (>) :: T x y a a -> T x y a b -> T x y a b # (<*) :: T x y a a -> T x y a b -> T x y a a #

A query using input of type a and yielding an output of type b

type Query a b = a ⟿ b Source #

Non-infix alias of ⟿

aggregatePair :: T x y a b -> T x y c d -> T x y (a, c) (b, d) Source #

We can merge any two arbitrary mget queries.

remember :: T x y a b -> T x y a (a, b) Source #

And we can remember the lookup

runT :: Functor f => ([x] -> f [y]) -> T x y a b -> a -> f b Source #

Reify aggregation into a target functor.