Binary Tree Catamorphism
HTML
<script src="https://rawgit.com/eu81273/jsfiddle-console/master/console.js"></script>
JavaScript
var n = (l, v, r) => ({
l: l,
v: v,
r: r,
map: f => n(l.map(f), f(v), r.map(f)),
});
var lf = v => ({
v: v,
map: f => lf(f(v)),
});
var inst = n(lf(2), 2, lf(3));