In the <textarea> on the left, define an ES6
generator. In the middle, you can wrap this generator using
Lazy(generator) and then map,
filter, etc. to your heart's content. The resulting
sequence will be evaluated and shown on the right.
This demo requires a browser which supports ES6 Generators.
Oh an by the way, in case you were wondering: this demo uses lemming.js to evaluate the code you enter in the editors below. (And the editors use CodeMirror.)