Discussion on: A simple explanation of functional pipe in JavaScript

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Replies for: Not data last.

Why is data last important? If the function composition grows (multi-line), it can be annoying to go to the end just to see what is passed in at the beginning. Chronological ordering is more readable. If it doesn't pose a clear disadvantage, I don't see why not use it.

mister. jones • Dec 22 '20

From what I understand of functional programming, currying typically uses a data-last approach.

It's nice, because it allows you to create functions from composed functions. So, yes, if you're piping a lot of functions into your pipeline, it could be annoying to have to find the end-of-the-line to check what data is actually being piped through. But, I'd argue that if you're piping that many functions through, you should consider making it into a named function anyway, so that readers don't have to parse through every step to understand what it's ultimately doing.

Manuel Romero already posted a slugify function (above) as an example, so I'll riff on that:

const pipe = (...fns) => x => fns.reduce((y, f) => f(y), x);

const toLowerCase = str => str.toLowerCase()
const split = separator => str => str.split(separator)
const join = separator => arr => arr.join(separator)

const slugify = pipe(
  String,
  toLowerCase,
  split(' '),
  join('-')
)

fooBarSlug = slugify('Foo Bar Fizz Buzz')
console.log(fooBarSlug)  // foo-bar-fizz-buzz