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https://github.com/lasp-lang/lasp

Prototype implementation of Lasp in Erlang.
https://github.com/lasp-lang/lasp

crdt distributed-systems erlang lasp

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Prototype implementation of Lasp in Erlang.

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README

        

Lasp
=======================================================

[![Build Status](https://travis-ci.org/lasp-lang/lasp.svg?branch=master)](https://travis-ci.org/lasp-lang/lasp)

## Overview

Lasp is a programming model for synchronization-free computations.

## Installing

Lasp requires Erlang 19 or greater. Once you have Erlang installed, do
the following to install and build Lasp.

```
$ git clone [email protected]:lasp-lang/lasp.git
$ cd lasp
$ make
```

## Creating a small cluster
Clone Lasp:
```
$ git clone https://github.com/lasp-lang/lasp.git
```

Run two shells
```
$ rebar3 shell --name [email protected]
$ rebar3 shell --name [email protected]
```

Exceute to node a:
```erlang
1> lasp_peer_service:join('[email protected]').
ok
2> lasp_peer_service:members().
{ok,['[email protected]','[email protected]']}
```

Execute node b:
```erlang
1> lasp_peer_service:members().
{ok,['[email protected]','[email protected]']}
```

Go back to node a and run:
```erlang
3> Content = #{what => i_am_an_awmap_value}.

% create a lasp CRDT
AwMapVarName = <<"awmap">>.
Key1 = <<"key1">>.
AwMapType = {state_awmap, [state_mvregister]}.
{ok, {AwMap, _, _, _}} = lasp:declare({AwMapVarName, AwMapType}, AwMapType).

% Update the CRDT with the content
{ok, _} = lasp:update(AwMap, {apply, Key1, {set, nil, Content}}, term_to_binary(self())).
```

Go to node b and retrieve the content of the CRDT:
```erlang
2> {ok,[{_, AwMapSet}]} = lasp:query({<<"awmap">>,{state_awmap,[state_mvregister]}}).

3> sets:to_list(AwMapSet).
% [#{what => i_am_an_awmap_value}]
```

## Running a shell

You can run a Erlang shell where you can interact with a Lasp node by
doing the following:

```
$ make shell
```

## Running the test suite

To run the test suite, which will execute all of the Lasp scenarios, use
the following command.

```bash
$ make check
```

## Notes

If using the Distributed Erlang backend, make sure that all nodes are configured to use the same cookie.

## Code examples

[This blog post](http://marianoguerra.org/posts/playing-with-lasp-and-crdts.html) by [@marianoguerra](https://github.com/marianoguerra) contains concise sample code.