y-combinator
is one of the fixed-point combinators in untyped lambda calculus
All credits go to Haskell Curry.
Installation | Annotated source | Example | License
Installation
npm install y-combinator
Annotated source
I have no idea what is the Y combinator operator (maybe one day I will :P), I have just stolen the code from a guy called Douglas Crockford a.k.a Walker Texas JS.
Here it is the code, it is a function that consumes a function and returns a function, that consumes a function that returns a function ...
function Y(le) {
return (function (f) {
return f(f)
}(function (f) {
return le(function (x) {
return f(f)(x)
})
}))
}
... ok, now export the Y function
module.exports = Y
Example
Q. What can I do with the Y Combinator?
A. Mmh, for example you can use it to get a factorial function, the following code works!
var Y = require('y-cominator')
var factorial = Y(fac => n => n <= 2 ? n : n * fac(n - 1))
console.log(factorial(5)) // 120