In our applications it is often useful to be able to represent the possible absence of a value. In JavaScript we have undefined to represent the result of trying to access something that was never defined to begin with, and we havenull to assign to values that might have a value but could also be empty. These two are often conflated and used interchangeably both at the core language level and in libraries, but both are used to communicate the lack of a value where it is possible to find one.

For example, consider the function Array.prototype.find

Heads up: this post is way old, I’m just cross-posting it. It was originally written in March 2016 which is basically the Roman Empire on frontend programming timelines. Also I was not good at writing then. I’m still not, but I wasn’t then either.

What do we do when configuration objects grow large or hard to understand? In this article we'll examine some cases where this happens and how to use the forward apply operator with some basic patterns create beautifully readable configuration builders.

The (|>) operator is, in my opinion, one of the most elegant features of the Elm…

Luke Westby

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