ECMAScript back end for Functional Reactive Programming in Agda
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An implementation of Functional Reactive Programming for building HTML applications in Agda.

To build and application, start with an HTML file:

      <title>Hello World</title>
      <script data-main="agda.frp.main" src="require.js"></script>
      <h1>A greeting</h1>
      <p class="agda" data-agda="Demo.Hello"></p>

This is just a regular old HTML file, which loads the agda.frp.main JavaScript module (using require.js, but any AMD-compliant JavaScript module loader should work). The important part is:

  <p class="agda" data-agda="Demo.Hello"></p>

The "agda" class and data-agda attribute indicates that an Agda program should be executed inside the annotated node.

Now write an Agda program:

  open import FRP.JS.Behaviour using ( Beh ; [_] )
  open import FRP.JS.DOM using ( DOM ; text )
  open import FRP.JS.RSet using ( ⟦_⟧ )

  module Demo.Hello where
  main :  {w}  ⟦ Beh (DOM w) ⟧
  main = text ["Hello, world."]

This program creates a text node whose content is always "Hello, World."

Compile (using the darcs snapshot of Agda 2.2.11):

  agda --js Demo/Hello.agda

this will create a bunch of js files such as jAgda.Demo.Hello.js.

Put all the .js files (including require.js and the agda.frp.*.js files) in the same directory as hello.html.

Load hello.html in a browser, and enjoy.

There are unit tests in FRP.JS.Test, which link against John Resig's QUnit ( To run the tests, first "make tests", then load build/tests.html in a browser.