The web3 package

[Tags:bsd3, library, test]

Web3 is a Haskell client library for Ethereum

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Dependencies aeson (>= && <1.1), attoparsec (>= && <0.14), base (>4.8 && <4.11), base16-bytestring (>= && <0.2), bytestring (>= && <0.11), cryptonite (==0.21.*), http-client (>=0.5.5 && <0.6), http-client-tls (>= && <0.4), memory (>=0.14.1 && <0.15), template-haskell (>= && <2.12), text (>= && <1.3), transformers (>= && <0.6), vector (>= && <0.12) [details]
License BSD3
Copyright Alexander Krupenkin
Author Alexander Krupenkin
Category Network
Home page
Source repository head: git clone
Uploaded Fri Feb 24 12:16:31 UTC 2017 by akru
Distributions NixOS:
Downloads 364 total (77 in the last 30 days)
0 []
Status Docs available [build log]
Last success reported on 2017-02-24 [all 1 reports]
Hackage Matrix CI




Maintainer's Corner

For package maintainers and hackage trustees

Readme for web3

Readme for web3-

Ethereum Haskell API

This is the Ethereum compatible Haskell API which implements the Generic JSON RPC spec.

Build Status Build status Hackage Hackage Dependencies Haskell Programming Language BSD3 License


$ git clone && cd hs-web3
$ stack setup
$ stack ghci

This library runs only paired with geth or parity Ethereum node, please start node first before using the library.

Web3 monad

Any Ethereum node communication wrapped with Web3 monadic type.

> :t web3_clientVersion
web3_clientVersion :: Provider a => Web3 a Text

To run this computation used runWeb3' or runWeb3 functions.

> runWeb3 web3_clientVersion
Right "Parity//v1.4.5-beta-a028d04-20161126/x86_64-linux-gnu/rustc1.13.0"

Function runWeb3 use default Web3 provider at localhost:8545.

> :t runWeb3
  :: MonadIO m => Web3 DefaultProvider b -> m (Either Web3Error b)

TemplateHaskell generator

Quasiquotation is used to parse contract ABI or load from JSON file. TemplateHaskell driven Haskell contract API generator can automatical create instances for Event and Method typeclasses and function helpers.

> :set -XQuasiQuotes
> putStr [abiFrom|data/sample.json|]
                0x03de48b3 runA1()
                0x90126c7a runA2(string,uint256)

See example of usage.

import Data.Text (unpack)
import Text.Printf


main :: IO ()
main = do
    Right s <- runWeb3 $ do
        n <- name token
        s <- symbol token
        d <- decimals token
        return $ printf "Token %s with symbol %s and decimals %d"
                        (unpack n) (unpack s) d
    putStrLn s
  where token = "0x237D60A8b41aFD2a335305ed458B609D7667D789"