Data.MemoCombinators (original) (raw)

Description

This module provides combinators for building memo tables over various data types, so that the type of table can be customized depending on the application.

This module is designed to be imported qualified, eg.

import qualified Data.MemoCombinators as Memo

Usage is straightforward: apply an object of type Memo a to a function of type a -> b, and get a memoized function of type a -> b. For example:

fib = Memo.integral fib' where fib' 0 = 0 fib' 1 = 1 fib' x = fib (x-1) + fib (x-2)

Synopsis

• type Memo a = forall r. (a -> r) -> a -> r
• wrap :: (a -> b) -> (b -> a) -> Memo a -> Memo b
• memo2 :: Memo a -> Memo b -> (a -> b -> r) -> a -> b -> r
• memo3 :: Memo a -> Memo b -> Memo c -> (a -> b -> c -> r) -> a -> b -> c -> r
• memoSecond :: Memo b -> (a -> b -> r) -> a -> b -> r
• memoThird :: Memo c -> (a -> b -> c -> r) -> a -> b -> c -> r
• bool :: Memo Bool
• char :: Memo Char
• list :: Memo a -> Memo [a]
• boundedList :: Int -> Memo a -> Memo [a]
• either :: Memo a -> Memo b -> Memo (Either a b)
• maybe :: Memo a -> Memo (Maybe a)
• unit :: Memo ()
• pair :: Memo a -> Memo b -> Memo (a, b)
• enum :: Enum a => Memo a
• integral :: Integral a => Memo a
• bits :: (Num a, Ord a, Bits a) => Memo a
• switch :: (a -> Bool) -> Memo a -> Memo a -> Memo a
• type RangeMemo a = (a, a) -> Memo a
• arrayRange :: Ix a => RangeMemo a
• unsafeArrayRange :: Ix a => RangeMemo a
• chunks :: Ix a => RangeMemo a -> [(a, a)] -> Memo a

Documentation

type Memo a = forall r. (a -> r) -> a -> rSource

The type of a memo table for functions of a.

wrap :: (a -> b) -> (b -> a) -> Memo a -> Memo bSource

Given a memoizer for a and an isomorphism between a and b, build a memoizer for b.

memo2 :: Memo a -> Memo b -> (a -> b -> r) -> a -> b -> rSource

Memoize a two argument function (just apply the table directly for single argument functions).

memo3 :: Memo a -> Memo b -> Memo c -> (a -> b -> c -> r) -> a -> b -> c -> rSource

Memoize a three argument function.

memoSecond :: Memo b -> (a -> b -> r) -> a -> b -> rSource

Memoize the second argument of a function.

memoThird :: Memo c -> (a -> b -> c -> r) -> a -> b -> c -> rSource

Memoize the third argument of a function.

switch :: (a -> Bool) -> Memo a -> Memo a -> Memo aSource

switch p a b uses the memo table a whenever p gives true and the memo table b whenever p gives false.

type RangeMemo a = (a, a) -> Memo aSource

The type of builders for ranged tables; takes a lower bound and an upper bound, and returns a memo table for that range.

arrayRange :: Ix a => RangeMemo aSource

Build a memo table for a range using a flat array. If items are given outside the range, don't memoize.

chunks :: Ix a => RangeMemo a -> [(a, a)] -> Memo aSource

Given a list of ranges, (lazily) build a memo table for each one and combine them using linear search.