tardis: Bidirectional state monad transformer

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A Tardis is a combination of both a forwards and a backwards state transformer, providing two state values that "travel" in opposite directions.

A detailed description of what a Tardis is and how to use it can be found in the documentation for Control.Monad.Tardis.

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Control
- Monad
  - Control.Monad.Tardis
    - Control.Monad.Tardis.Class
  - Trans
    - Control.Monad.Trans.Tardis

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tardis-0.5.0.tar.gz [browse] (Cabal source package)
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Versions [RSS]	0.2.0.0, 0.3.0.0, 0.4.1.0, 0.4.2.0, 0.4.3.0, 0.4.4.0, 0.5.0
Change log	ChangeLog.md
Dependencies	base (>=4.8 && <5), mmorph (>=1 && <2), mtl (>=2 && <3) [details]
Tested with	ghc ==9.8.1, ghc ==9.6.3, ghc ==9.4.8
License	BSD-3-Clause
Author	Dan Burton
Maintainer	danburton.email@gmail.com
Category	Control
Home page	https://github.com/DanBurton/tardis
Bug tracker	https://github.com/DanBurton/tardis/issues
Source repo	head: git clone git://github.com/DanBurton/tardis.git this: git clone git://github.com/DanBurton/tardis.git(tag tardis-0.4.1.0)
Uploaded	by DanBurton at 2024-01-16T00:58:12Z
Distributions	NixOS:0.5.0, Stackage:0.5.0
Reverse Dependencies	5 direct, 3 indirect [details]
Downloads	4883 total (36 in the last 30 days)
Rating	2.0 (votes: 1) [estimated by Bayesian average]
Your Rating	λ λ λ
Status	Docs available [build log] Last success reported on 2024-01-16 [all 1 reports]

Readme for tardis-0.5.0

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TardisT

The State monad allows you to send information forwards to the future, or to receive such information from the past. The Reverse State monad allows you to do the reverse: send information backwards to the past, or receive information from the future.

TardisT is a monad transformer that provides state operations that allow you to send information to both the future and the past, as well as receive information from both directions. It is isomorphic to a StateT on top of a ReverseStateT, or vice-versa.

See test/Example.hs for an example.

This was inspired by Luke Palmer's blog post on the "reverse state monad".

http://lukepalmer.wordpress.com/2008/08/10/mindfuck-the-reverse-state-monad/