crjdt-haskell

A Conflict-Free Replicated JSON Datatype for Haskell


Keywords
bsd3, library, test, Data.Crjdt, Data.Crjdt.Context, Data.Crjdt.Eval, Data.Crjdt.Internal, Data.Crjdt.Internal.Core, Data.Crjdt.Types, paper, haddocks, second version, Scala CRJDT, crdt, haskell, json
License
BSD-3-Clause
Install
cabal install crjdt-haskell-0.3.0

Documentation

Build Status

A Conflict-Free Replicated JSON Datatype for Haskell

crjdt-haskell provides high level interface to CRDT which is formalised in the paper by Martin Kleppmann and Alastair R. Beresford.

Documentation

See haddocks.

Example

{-# LANGUAGE OverloadedStrings #-}

module Main where

import Data.Crjdt as C

-- Original state
original :: Command ()
original = doc .> key "key" =: "A"

-- First replica updates doc["key"] to "B"
replica1 :: Command ()
replica1 = original *> doc .> key "key" =: "B"

-- Second replica updates doc["key"] to "C"
replica2 :: Command ()
replica2 = original *> doc .> key "key" =: "C"

main :: IO ()
main = do
  -- Sync first and second replica
  let Right (r1, r2) = sync (1, replica1) (2, replica2)

  let replica1' = execEval 1 r1
      replica2' = execEval 2 r2

  -- Both replicas converge to: {"key": {"B", "C"}}
  print (document replica1' == document replica2') -- True

Future work

  • Improve documentation
  • Aeson support
  • Simplify API as described in second version of the paper

Other implementations

LICENSE

Copyright © 2017 Amar Potghan

Distributed under BSD License.