web3: Ethereum API for Haskell

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Web3 is a Haskell client library for Ethereum

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Change log CHANGELOG.md
Dependencies aeson (>= && <1.4), async (>= && <2.3), base (>4.9 && <4.12), basement (>=0.0.7 && <0.1), bytestring (>= && <0.11), cereal (>= && <0.6), cryptonite (==0.25.*), data-default (>= && <0.8), exceptions (>=0.8.3 && <0.11), generics-sop (>= && <0.4), http-client (>= && <0.6), http-client-tls (>= && <0.4), machines (>=0.6.3 && <0.7), memory (>=0.14.16 && <0.15), mtl (>=2.2.2 && <2.3), parsec (>= && <3.2), tagged (>=0.8.5 && <0.9), template-haskell (>= && <2.14), text (>= && <1.3), transformers (>= && <0.6) [details]
License BSD-3-Clause
Copyright Alexander Krupenkin
Author Alexander Krupenkin
Maintainer mail@akru.me
Category Network
Home page https://github.com/airalab/hs-web3#readme
Source repo head: git clone https://github.com/airalab/hs-web3
Uploaded by akru at Tue May 22 14:26:06 UTC 2018
Distributions NixOS:
Downloads 2279 total (100 in the last 30 days)
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Status Docs available [build log]
Last success reported on 2018-05-22 [all 1 reports]
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Maintainer's Corner

For package maintainers and hackage trustees

Readme for web3-

[back to package description]

Ethereum Haskell API

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

Build Status Build status Hackage Haskell Programming Language BSD3 License Code Triagers Badge


$ git clone https://github.com/airalab/hs-web3 && 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.

> import Network.Ethereum.Web3.Web3
> :t clientVersion
clientVersion :: Web3 Text

To run this computation used runWeb3' or runWeb3 functions.

> import Network.Ethereum.Web3
> runWeb3 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 a -> m (Either Web3Error a)

TemplateHaskell generator

Quasiquotation is used to parse contract ABI or load from JSON file. TemplateHaskell driven Haskell contract API generator can automatical create ABI encoding instances and contract method helpers.

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

Use -ddump-splices to see generated code during compilation or in GHCi. See examples folder for more use cases.


Testing the web3 is split up into two suites: unit and live. The unit suite tests internal library facilities, while the live tests that the library adequately interacts with a Web3 provider.

One may simply run stack test to run both suites, or stack test web3:unit or stack test web3:live to run the test suites individually.

The unit suite has no external dependencies, while the live suite requires Truffle and jq to be available on your machine.

The live suite also requires a Web3 provider with Ethereum capabilities, as well as an unlocked account with ether to send transactions from. It uses Truffle to deploy testing contracts, generating ABIs for them in the process, then using said ABIs as part of a TemplateHaskell step in the suite. It is assumed that the provider is available at http://localhost:8545. If that's not the case, you must update truffle.js so that Truffle can deploy the contracts correctly, and pass the WEB3_PROVIDER=http://host:port environment variable when running the tests so that the web3 library can interact with the chain that's being tested against.