The acme-realworld package

[ Tags: acme, bsd3, library ] [ Propose Tags ]

GHC represents an IO action internally as a function from one state of the world to the next:

State# RealWorld -> (# State# RealWorld, a #)

This module provides a very useful capability stemming directly from this representation: the ability to save the current state of the universe and restore it later. This provides a way to "undo" certain types of side effects in the IO monad:

import Acme.Missiles
import Acme.RealWorld

main :: IO ()
main = do
    -- Save the current state of the universe
    world_as_we_know_it <- getWorld

    -- Cause serious international side effects
    launchMissiles

    -- After realizing that was a terrible, terrible mistake, restore the
    -- pre-war state of the universe.
    putWorld world_as_we_know_it

Properties

Versions 0.1, 0.1.1
Dependencies base (==4.*) [details]
License BSD3
Copyright Copyright (c) Joseph Adams 2011
Author Joey Adams
Maintainer joeyadams3.14159@gmail.com
Category Acme
Uploaded Fri Dec 9 09:01:13 UTC 2011 by JoeyAdams
Distributions NixOS:0.1.1
Downloads 846 total (39 in the last 30 days)
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