The library provides a Memoizer type class similar to Representable
(from adjunctions)
that is suitable for containers with size known only at runtime. The only difference between
those type classes is that Memoizer passes helper information to the tabulate function.
{-# LANGUAGE TypeFamilies #-}
class Memoizer t where
-- Rep t
type Arg t
-- Helps memoizer to know all possible function inputs.
type DomainHint t
-- tabulate
remember :: (Arg t -> a) -> DomainHint t -> t a
-- index
recall :: t a -> Arg t -> a
recallMaybe :: t a -> Arg t -> Maybe a
{-# MINIMAL remember, (recall | recallMaybe) #-}| Data type | Arg |
DomainHint |
Does support unsafe indexing? |
|---|---|---|---|
any Representable Functor |
Representable f => Rep f |
() (none) |
|
Array, UArray |
Ix i => i |
Ix i => (i, i) (range of the array) |
Yes |
boxed/unboxed/storable Vector |
Int |
Int (length of the array) |
Yes |
HashMap |
(Hashable k, Eq k) => k |
(Hashable k, Eq k) => [k] (all the function inputs) |
|
Map |
Ord k => k |
Ord k => [k] (all the function inputs) |
|
IntMap |
Int |
[Int] (all the function inputs) |
The library also provides StoreT comonad transformer that uses Memoizer under the hood.
data StoreT memoizer w a
= StoreT (w (memoizer a)) (DomainHint memoizer) (Arg memoizer)The source code has a few Haddock documentation, so you can run stack haddock to render it.