plusOne(a) {
    return a[fl.map](function(value) {return value + 1})
}</code></pre>
<p>Now this method works with any Fantasy Land compliant <a href="https://github.com/fantasyland/fantasy-land#functor">Functor</a>, such as <a href="https://github.com/ramda/ramda-fantasy/blob/master/docs/Maybe.md"><code>R.Maybe</code></a>, <a href="https://github.com/sanctuary-js/sanctuary#either-type"><code>S.Either</code></a>, <code>stream</code>, etc.</p>
<p>This example may seem convoluted, but it&#39;s a trade-off in 