const

The constant function from functional programming: it takes a value and returns a function that will return that value:

Usage no npm install needed!

<script type="module">
  import const from 'https://cdn.skypack.dev/const';
</script>

README

const

The constant function from functional programming: it takes a value and returns a function that will return that value:

var constant = require('const')
var alwaysA = constant('a');

alwaysA() //= 'a'

Useful to lifting a value into the world of functions, e.g. when using promises:

getUserDetails()
    .then(getMessageFromUser, constant('User not found'))

Other names it's gone by in the past:

  • K combinator
  • lift
  • always