Trampolining TCO functions in JS examples

trampoline.js

/*
 * aperture function modelled after https://ramdajs.com/docs/#aperture
 */

const head = xs => xs[0]
const last = xs => xs[xs.length - 1]
const tail = xs => xs.slice(1)
const isEmpty = xs => xs.length == 0

/* A recursive aperture implementation
 *
 *
 * Usage examples:
 * recursive_aperture([1,2,3,4,5,6,7,8,9], 4)
 *    => [ [ 1, 2, 3, 4 ], [ 2, 3, 4, 5 ], [ 3, 4, 5, 6 ], [ 4, 5, 6, 7 ], [ 5, 6, 7, 8 ], [ 6, 7, 8, 9 ] ]
 * recursive_aperture([1,2,3,4,5,6,7,8,9], 3)
 *    => [ [ 1, 2, 3 ], [ 2, 3, 4 ], [ 3, 4, 5 ], [ 4, 5, 6 ], [ 5, 6, 7 ], [ 6, 7, 8 ], [ 7, 8, 9 ] ]
 *
 */
function recursive_aperture(seq, n, acc=[]) {
  if (isEmpty(seq)) {
    return acc
  }

  if (isEmpty(acc)) { 
    return recursive_aperture(seq.slice(n), n, [seq.slice(0, n)])
  }

  rem = last(acc).slice(1)
  acc = acc.concat([rem.concat([head(seq)])])
  return recursive_aperture(tail(seq), n, acc)
}

/*
 * A function that trampolines between its function argument based on returned result
 */

function trampoline(fn) {
  return function(...args) {
    let nextArgs = args
    while (true) {
      let result = fn.apply(this, nextArgs)
      proceed = result[0]
      nextArgs = result[1]
      if (!proceed) {
        return nextArgs
      }
    }
  }
}

/*
 * The aperture function re-written to use the trampoline
 *
 * Examples:
 * trampoline(aperture)([1,2,3,4,5,6,7,8,9], 2)
 *   => [ [ 1, 2 ], [ 2, 3 ], [ 3, 4 ], [ 4, 5 ], [ 5, 6 ], [ 6, 7 ], [ 7, 8 ], [ 8, 9 ] ]
 * trampoline(aperture)([1,2,3,4,5,6,7,8,9], 4)
 *   => [ [ 1, 2, 3, 4 ], [ 2, 3, 4, 5 ], [ 3, 4, 5, 6 ], [ 4, 5, 6, 7 ], [ 5, 6, 7, 8 ], [ 6, 7, 8, 9 ] ]
 */
function aperture(seq, n, acc=[]) {
  if (isEmpty(seq)) {
    return [false, acc]
  }

  if (isEmpty(acc)) { 
    return [true, [seq.slice(n), n, [seq.slice(0, n)]]]
  }

  rem = last(acc).slice(1)
  acc = acc.concat([rem.concat([head(seq)])])
  return [true, [tail(seq), n, acc]]
}