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A minimalist C library for working with Sheens

Summary

A minimalist Sheens implementation in ECMAScript that's executed by Duktape and wrapped in a C library. Yes, that does sound a little odd.

The stripped 32-bit demo executable is 360KB. The core ECMAScript code (un-minified) is less than 40KB (11KB minified). An experimental nodejs module is available (via make nodejs).

See that Sheens repo for more documentation about these machines.

License

This repo is licensed under Apache License 2.0.

API

See machines.h.

A demo

For now, running the demo requires two tools written in Go, so you need Go installed to build this demo. (We'll remove this unncessary dependency soon.)

go get github.com/bronze1man/yaml2json
go get github.com/tdewolff/minify/cmd/minify
make demo
./demo

Another demo

This demo is a simple process that reads messages from stdin and writes output to stdout.

make specs/turnstile.js specs/double.js sheensio

# Define a "crew" of two machines.
cat<<EOF > crew.json
{"id":"simpsons",
 "machines":{
   "doubler":{"spec":"specs/double.js","node":"listen","bs":{"count":0}},
   "turnstile":{"spec":"specs/turnstile.js","node":"locked","bs":{}}}}
EOF

# Send messages to that crew.
cat<<EOF | ./sheensio -d
{"double":1}
{"double":10}
{"double":100}
{"input":"push"}
{"input":"coin"}
{"input":"coin"}
{"input":"push"}
EOF

The above is in demo.sh.

Yet another demo

This demo shows how to do some primitive Sheens work from Javascript (demo.js).

make demo
./demo driver.js demo.js

Utilities

The driver executable will execute (mach_eval) code in files given on the command line. The environment includes what's in the directory js and in the file driver.js, so you can experiment directly with those functions. For example, if the file check.js contains

JSON.stringify(match(null, {"likes":"?x"}, {"likes":"tacos"}, {}));

Then

./driver check.js

should write

[{"?x":"tacos"}]

Per the documentation for mach_eval, the code that's executed should return a string.

Discussion

Routing

driver.js implements optional routing that can present a message only to machines specified in that message. If a message has a "to" property, the value should be a string or an array of strings. The message is then only presented to the machine or machines with those ids.

For example, {"to":"doubler","double":1} will only be sent to a machine with id doubler (if it exists). The message {"to":["this","that"],...} will only be presented to the machines with ids this and that (if they exist). Note that the entire message (including the "to" property) is still present to the target machines.

Nodejs

Little Sheens has some crude support for Node.js.

make nodejs

That command might make the Node module node-littlesheens. This example Jupyter notebook demonstrates a little of the available functionality.

"Lua programs can also be little"

A start at a Lua-based Little Sheens? (Should end up in another repo if worthy.)

docker

Use the following to set up docker container for dev environment.

docker build -t gears/littlesheens:latest .
docker run -i -t -v $HOME/go:/go gears/littlesheens:latest /bin/bash

Code of Conduct

We take our code of conduct seriously. Please abide by it.

Contributing

Please read our contributing guide for details on how to contribute to our project.

References

  1. Sheens
  2. Duktape