nondeterminism: A monad and monad transformer for nondeterministic computations.

[ ai, constraints, control, failure, library, monads ] [ Propose Tags ]

Nondeterministic computations


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Versions [faq] 1.0, 1.2, 1.4
Dependencies base (>=4.8 && <5), containers, mtl (>=2 && <2.3) [details]
License LicenseRef-LGPL
Author Andrei Barbu <andrei@0xab.com>
Maintainer Andrei Barbu <andrei@0xab.com>
Revised Revision 1 made by HerbertValerioRiedel at Sat Jun 1 09:03:45 UTC 2019
Category Control, AI, Constraints, Failure, Monads
Source repo head: git clone http://github.com/abarbu/nondeterminism-haskell
Uploaded by AndreiBarbu at Mon Oct 19 18:04:43 UTC 2015
Distributions LTSHaskell:1.4, NixOS:1.4, Stackage:1.4
Downloads 1471 total (71 in the last 30 days)
Rating 2.0 (votes: 1) [estimated by rule of succession]
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Status Hackage Matrix CI
Docs available [build log]
Last success reported on 2015-10-19 [all 1 reports]

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Readme for nondeterminism-1.2

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Nondeterminism

This package is available via Hackage where its documentation resides.

This provides nondeterministic computations in Haskell. It implements an Amb monad in which you can perform nondeterministic choices along with a monad transformer version, AmbT.

Amb

An example which finds Pythagorean triplets up to a certain size, project Euler problem 9.

import Control.Monad
import Control.Monad.Amb
pyTriple :: (Num t, Ord t) => t -> Amb r (t, t, t)
pyTriple n = do a <- anIntegerBetween 1 n
                b <- anIntegerBetween (a + 1) n
                c <- anIntegerBetween (b + 1) n
                when (a*a + b*b /= c*c) empty
                return (a,b,c)
length $ allValues $ pyTriple 100

More examples can be found in tests/test.hs.

Future

  • allValues is not lazy in its return value