Same as Html.lazy. In case you're unfamiliar, here's a note from the Html library!

Since all Elm functions are pure we have a guarantee that the same input
will always result in the same output. This module gives us tools to be lazy
about building `Html` that utilize this fact.


Rather than immediately applying functions to their arguments, the `lazy`
functions just bundle the function and arguments up for later. When diffing
the old and new virtual DOM, it checks to see if all the arguments are equal
by reference. If so, it skips calling the function!


This is a really cheap test and often makes things a lot faster, but definitely
benchmark to be sure!

Note: For now only lazy that covers one argument can be provided. In 0.19 this will change!