December 7, 2018

259 words 2 mins read



Simple blockchain server written in haskell

repo name aviaviavi/legion
repo link
language Haskell
size (curr.) 34 kB
stars (curr.) 605
created 2017-04-12
license MIT License

Legion - a simple blockchain implementation

Build Status

An as-simple-as-possible blockchain server inspired by naivechain, but written in Haskell. Spinning up several Legion nodes creates a peer to peer network that syncronizes the block chain across the network.

Prereqs: To compile from source, you’ll need stack.

Alternatively, you can get a precompiled pre-release binary. Note: if you download the binary from github, you’ll need to mark it executable by running:

$ chmod +x legion-exe


$ stack exec legion-exe [http port] [p2p port] [optional: `seedhost:seedP2PPort`]


$ stack exec legion-exe 8001 9001

By default, legion will log what it’s doing to standard out. In another terminal window:

$ stack exec legion-exe 8002 9002 localhost:9001

Alternatively, you grab the binaries from the github releases, and run that directly rather than via stack exec

The 3rd argument tells the node where a seed node can be found to bootstrap the connection to the peer to peer network. The current state of the (valid) blockchain will be fetched from all servers, and it will automatically keep itself updated and post its own updated to others.

Now that 2 nodes are now synced, and you can view the current chain from either node at http://localhost:$httpPort/chain, eg http://localhost:8001/chain

Add a new block to the blockchain via a POST request to /block:

$ curl -H "Content-Type: application/json" -X POST -d '{"blockBody": "this is the data for the next block"}' http://localhost:8001/block
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