Consider the working code below:
var randN = x => () => Math.floor(x*Math.random());
var rand10 = randN(10)
times(rand10, 10) // => [6, 3, 7, 0, 9, 1, 7, 2, 6, 0]
randN is a function that takes a number and returns an RNG that, when called, will return a random int in the range [0, N-1]. So it's a factory for specific RNGs.
I've been using ramda.js, and learning functional programming theory, and my question is: Is it possible to rewrite randN in a point free style using ramda?
For example, I could write:
var badAttempt = pipe(multiply(Math.random()), Math.floor)
This would satisfy the "point-free style" requirement, but fails to behave the same way as randN: calling badAttempt(10) simply returns a single random number between 1 and 10, rather than a function that generates a random number between 1 and 10 when called.
I have not been able to find a combination of ramda functions that enables me to do the rewrite in a point-free style. I can't tell if this is just a failure on my part, or something special about using random, which breaks referential transparency and therefore may be incompatible with a point free style.
update
my own slight variation on the solution, after discussing it with Denys:
randN = pipe(always, of, append(Math.random), useWith(pipe(multiply, Math.floor)), partial(__,[1,1]))