nfriend / cooltojs

A Cool-to-JavaScript transpiler, written in TypeScript

cooltojs

A Cool-to-JavaScript transpiler, written in TypeScript.

Example usage

<script type="text/cool" src="HelloWorld.cl"></script>
<script src="cooltojs-1.0.1.js"></script>
<script>

    // automatically fetch any Cool source referenced
    // by a <script type="text/cool"> element
    CoolToJS.GetReferencedCoolSources(function(sources) {

        // transpile the source
        var transpilerOutput = CoolToJS.Transpile({
            coolProgramSources: sources
        });

        if (transpilerOutput.success) {

            // do what you want with the output
            eval(transpilerOutput.generatedJavaScript);
        }
    });
</script>

Setup

By default, the output of your Cool program will be redirected to console.log. You can specify a different output function with the out_string and out_int options:

var transpilerOutput = CoolToJS.Transpile({
    coolProgramSources: sources,
    out_string: function(output) {
        document.getElementById('output').innerHTML += output;
    },
    out_int: function (output) {
        document.getElementById('output').innerHTML += output;
    }
});

Similarly, you can provide input to your Cool program by providing in_string and in_int functions. These functions should accept an iterator object as a parameter. Once input has been entered by the user, the iterator's next() method should be invoked with the user's input. For example:

var myInputField = document.getElementById('my-input-field'),
    onlyNumbers = false,
    iterator;

myInputField.onkeydown = function(e) {
    if (e.which === 13 /* Enter */) {
        // if onlyNumbers === true, input should be validated
        // to ensure a valid number was entered

        iterator.next(myInputField.value)
        myInputField.value = '';
    }
}

var transpilerOutput = CoolToJS.Transpile({
    coolProgramSources: sources,
    in_string: function (newGenerator) {
        onlyNumbers = false;
        iterator = newGenerator;
    },
    in_int: function (newGenerator) {
        onlyNumbers = true;
        iterator = newGenerator;
    }
});

By default, the in_string and in_int functions are mapped to empty functions, so you won't be able to send input to your Cool program without providing these functions.

Output

The output of the CoolToJS transpiler is valid ES6 JavaScript. Note that support for ES6 is still fairly limited, so it's advisable to use a ES6 to ES5 compiler like Babel to generate code that can target current browsers. An example of this transformation using Babel:

<script type="text/cool" src="HelloWorld.cl"></script>
<script src="lib/babel/browser-polyfill.js"></script>
<script src="lib/babel/browser.js"></script>
<script src="cooltojs-1.0.1.js"></script>
<script>

    // automatically fetch any Cool source referenced
    // by a <script type="text/cool"> element
    CoolToJS.GetReferencedCoolSources(function(sources) {

        // transpile the source
        var transpilerOutput = CoolToJS.Transpile({
            coolProgramSources: sources
        });

        if (transpilerOutput.success) {

            // transform the generated ES6 code to ES5 code
            var es5Code = babel.transform(transpilerOutput.generatedJavaScript, {
                stage: 0
            }).code;

            // do what you want with the ES5 code
            eval(es5Code);
        }
    });
</script>

See the live version of this example at http://nathanfriend.io/cooltojs/example/.

Developing/running locally

1. If you haven't already, install Git and Node
2. Clone this repository
3. Inside the CoolToJS directory, run npm install
4. Build the transpiler by running npm run build. This will update the CoolToJS/cooltojs-X.X.X.* files.
5. To run the example site locally, run npx http-server inside the CoolToJS directory. This will start a local webserver (using the http-server npm package) and print the local URL to the site. Navigate to the URL in a browser and start transpiling 🚀