# Second Racket implementation of Syndicate

## Quickstart

    raco pkg install syndicate

or

    git clone https://git.syndicate-lang.org/syndicate-lang/syndicate-rkt
    cd syndicate-rkt
    make link

For more detail, [see below](#compiling-and-running-the-code).

## The language itself

This repository contains a [Racket](http://racket-lang.org/)
implementation of Syndicate, which includes

 - the implementation of the `#lang syndicate` language, in the
   [`syndicate` directory](syndicate/).

 - a TCP echo server example, which listens for connections on port
   5999 by default, in
   [`syndicate-examples/echo.rkt`](syndicate-examples/echo.rkt).
   Connect to it using, for example, `telnet localhost 5999`.

 - a number of other examples both small and large, in
   [`syndicate-examples/`](syndicate-examples/).

## New implementation

This is a reimplementation of Syndicate that takes the language-level
constructs of facets, endpoints, and fields to heart, integrating
knowledge of facets and endpoints into the dataspace implementation
itself.

It gains a *significant* performance advantage by doing so.

Programs seem to be about *20x faster* (compared to the
[previous implementation](https://git.syndicate-lang.org/syndicate-lang/syndicate-2017/src/branch/main/racket)).
Some are only 10x faster, some are 30x faster.

The implementation techniques herein are the subject of a forthcoming
paper. The prototype that embodies the new idea is in
[historical/prototype.rkt](historical/prototype.rkt), and
[syndicate/HOWITWORKS.md](syndicate/HOWITWORKS.md) describes the
approach via prose.

All the drivers end up looking much nicer with this new
implementation. The previously-separate GL-2D support is now
integrated as just another driver (though the timing characteristics
of the old implementation are not precisely preserved). The
[ground.rkt](syndicate/ground.rkt) implementation is much cleaner.

To see the difference in speed, try out the "many Racket logos"
animation example/demo after installing the `syndicate` and
`syndicate-examples` packages:

    racket -l syndicate-examples/gl-2d-many

Hopefully you'll get a smooth 60fps, though I admit I'm running it on
a fairly fast machine so you might need to drop the `sprite-count` in
the code a bit to sustain 60fps.

## Compiling and running the code

You will need Racket version 7.6 or later. (If you're using Racket CS,
you'll need version 7.8 or later because of
[this issue](https://github.com/racket/racket/issues/3132).)

Once you have Racket installed, run

    raco pkg install syndicate

to install the package from the Racket package repository, or

    raco pkg install --link syndicate

from the root directory of the Git checkout to install the package
from a local snapshot. This will make `#lang syndicate` available to
programs.

Repeat the process with `syndicate-examples` in place of `syndicate`
to install the examples as well.

Alternatively, `make link` from the root directory of the Git checkout
installs both packages from the local copy.

### Running the tests

The implementation test suite lives in [syndicate/test/](syndicate/test/). Run it with:

    raco setup syndicate; raco test -p syndicate

## Distribution

### License

This program is distributed under the terms of the [LGPLv3
license](https://opensource.org/licenses/lgpl-3.0.html) or any later version.

Documentation is distributed under the terms of the [CC BY 4.0
license](https://creativecommons.org/licenses/by/4.0/).

### Authors

* Tony Garnock-Jones

### Contributors

Contributors can be found inspecting the history of the source control
repository.

### How to contribute

As contributor, you retain the copyright of your work, but it must be
distributed using the same license of this software. For minor patches like bug
fixes, typos corrections, improvements in the documentation, this will be
implicit, and it will be documented in the history of the source control
repository. In case of major contributions, you must also update the header of the
modified source code files, specifying something like this:

```
SPDX-License-Identifier: LGPL-3.0-or-later
Copyright (C) 2019-2021 Previous Author <some.email@example.net>
Copyright (C) YYYY-YYYY New Contributor <some.email@example.net>
```