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Here are some lispyscript examples that run in node.js, in the browser, or both.

* Running in node.js

Lispyscript is a transpiler i.e. a compiler that translates from lispyscript to javascript.

The compiler command is named "lispy" (and actually - "lispy" does more than just compiling).

To see all of lispy's options enter (in a shell window):

  lispy --help

To run one of the examples in node you can start by compiling the .ls file e.g.:


This will produce the file "snippets.js".

Then you can run the javascript file with node:

  node snippets.js

Alternatively, you can run from .ls files directly using the lispy command in lieu of node with:

  lispy -r

Note:  "lispy -r" currently only works with simple examples which don't require other modules.

* Running in the browser:

As mentioned at lispy can (optionally) compile and run lispyscript code right in the browser.

See e.g. the "Run in the browser" example at:

Note that compiling in the browser is not recommended for production use as there's a performance overhead.

Yet you may find it useful for debugging or experimentation.

The "runinbrowser" directory here contains a copy of the example above.

To run this or other such "in browser" examples you must serve the files from a web server.

If you simply open the index.html file directly you will get an error due to cross origin ajax requests.

You can serve index.html from any web server you like - if you don't have one handy you can simply do:

    npm install http-server -g

Then from the root of the examples directory simply run:

    http-server .

Then to run an example hit it from your browser e.g.:


(if "browser-bundle.js" isn't found, make sure your web server is pointed at "examples" as it's doc root directory).

Additional note to lispyscript developers:

  The checked-in lib/browser-bundle.js file has been linked under the examples directory.

  There is no longer a need to do "lispy -b" to get a copy of browser-bundle.js when testing an example.

  Simply build the new browser-bundle.js file using e.g. "npm run prepublish".

* Trying the in-browser REPL

A version of the breakout game is also provided as a "run in browser" example.

This example is also setup with the "in-browser repl".

When served from a web server you hit this example with:


Once the page is displayed and running, hitting ctrl-v should open the repl at the right of your page.

(hitting ctrl-x would have opened it at the bottom)

A prompt should display where you can enter lispyscript commands much the same as the server-side "lispy" repl.

With the breakout game running see what happens when you enter e.g.:

    (set ballY 0)

Now you see - the in-browser repl is a way to cheat!! :)

If you were debugging this program, you might like to pause the game while you inspect it.  Try:

    (set pause true)

See what the current paddle position is by entering:


Try rendering the next frame by entering e.g.:


Up arrow and re-run "(drawFrame)" three times.  The ball should advance with each frame.

Start the game running again by entering:

    (set pause false)

Note:  The "pause" option is not part of the in-browser repl, that's a feature of the game's code.

Hit ctrl-v (or ctrl-x) again to toggle the repl closed.

You can toggle it open or closed as many times as you like, your command history will be remembered unless you refresh the page.

* Considerations re: "Run in browser" Modules versus Global Scoping:

The "inbrowser.html" version of the breakout game includes it's lispyscript inline in a script tag like: 

    <script type="text/lispyscript">(game code)</script>

This is not required to use the in-browser repl, it was just done for demonstration.

It would have worked just as well with an external .ls file like:

    <script type="text/lispyscript" id="breakout" src=""></script>

That style is used in the other example here in the "runinbrowser" directory.

Note however this script tag includes an "id" we did not include in our breakout example's script tag.

When you give an "id" you're saying to hide the variables of the code exactly as a node.js ("CommonJS") module would.

We chose to omit the "id" in the breakout example which is why the repl could see the game variables directly.

If we hadn't, we'd have had to do additional things at our repl command line like:

    (var breakout (require 'breakout'))

And defined a variable like "breakout" as a handle to access exported module variables.

If using the module style with "id", you might remove the "id" while using the in-browser repl, but put it back for production.

Or you might choose (as we've done in this example) to simply not use the "module" concept, especially for simple examples or a demo.

(thus making your in-browser lispyscript variables globally scoped, as javascript has traditionally been, for better and for worse!!)