runmemo: A simple memoization helper library
This library encourages you to do memoization in three separate steps:
Create a memoizable function
Create or select an appropriate memoizer
Run the memoizer on the memoizable function
Let's start with the first.
When you create a memoizable function,
you should use the self
convention,
which is that the first input to the function is self
,
and all recursive calls are replaced with self
.
One common convention that goes well with the self
convention
is using a helper function go
, like so:
fib :: Memoizable (Integer -> Integer) fib self = go where go 0 = 1 go 1 = 1 go n = self (n-1) + self (n-2)
Now for the second. For this example,
we need a Memoizer that can handle an Integer
input,
and an Integer
output. Data.MemoCombinators
provides
integral
, which handles any Integral
input, and
any output. Data.MemoUgly
provides memo
,
which can memoize any function a -> b
, given an Ord
instance
for a
.
Third, let's run our memoizers! Since we have decoupled the definition of the memoized function from its actual memoization, we can create multiple memoized versions of the same function if we so desire.
import qualified Data.MemoUgly as Ugly import qualified Data.MemoCombinators as MC fibUgly :: Integer -> Integer fibUgly = runMemo Ugly.memo fib fibMC :: Integer -> Integer fibMC = runMemo MC.integral fib
You could easily do the same with Data.MemoTrie.memo
,
Data.Function.Memoize.memoize
, etc.
Using this technique, you can create local memoized functions whose memo tables are garbage collected as soon as they are no longer needed.
Downloads
- runmemo-1.0.0.1.tar.gz [browse] (Cabal source package)
- Package description (as included in the package)
Maintainer's Corner
For package maintainers and hackage trustees
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Versions [RSS] | 1.0.0.0, 1.0.0.1 |
---|---|
Dependencies | None [details] |
License | BSD-3-Clause |
Copyright | (c) Dan Burton 2012 |
Author | Dan Burton |
Maintainer | danburton.email@gmail.com |
Category | Data |
Home page | https://github.com/DanBurton/runmemo |
Source repo | head: git clone git@github.com:DanBurton/runmemo.git this: git clone git@github.com:DanBurton/runmemo.git(tag runmemo-1.0.0.1) |
Uploaded | by DanBurton at 2013-11-28T21:16:58Z |
Distributions | LTSHaskell:1.0.0.1, NixOS:1.0.0.1, Stackage:1.0.0.1 |
Reverse Dependencies | 1 direct, 0 indirect [details] |
Downloads | 2824 total (11 in the last 30 days) |
Rating | (no votes yet) [estimated by Bayesian average] |
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Status | Docs available [build log] Successful builds reported [all 1 reports] |