How can the collection be accessed during a Ramda map?

Question

Given a very simple example:

R.map((a, b) => {
  console.log(a, b) // 1, undefined
}, [1, 2, 3])

How can I access the collection as a whole within the map?

A contrived example of using the collection might be:

R.map((item, collection) => {
  console.log(item === collection.length)
}, [1, 2, 3])

I could store it in a variable prior, but this is at the end of a chain of functions

Answer 1

R.map doesn't give you access to the collection inside the mapping function, but you could create a closure around the mapping function in order to give yourself an opportunity to assign a name to the collection.

((collection) => R.map((item) => {
  console.log(item === collection.length)
}, collection))([1, 2, 3]);

Answer 2

As the comments have suggested, there are good reasons Ramda does not include this by default. But there is a decorator called addIndex which adds the index and collection:

const fn = R.addIndex(map)((elt, idx, coll) => elt == coll.length);
fn([1, 2, 3]); //=> [false, false, true]