Module "trampoline"

Const trampoline

• trampoline<T>(f: T | Fn0<T | Fn0<T>>): T

• Takes a function returning either a no-arg function (thunk) or its already realized (non-function) result. Re-executes thunk for as long as it returns another function/thunk. Once a non-function result has been produced, trampoline returns that value itself.

  remarks

  If the final result should be function, it needs to wrapped (e.g. as a 1-elem array).

  This function should be used for non-stack consuming recursion. I.e. a trampoline is a form of continuation passing style and only ever consumes max. 2 extra stack frames, independent from recursion depth.

  example

  const countdown = (acc, x) =>
    x >= 0 ?
      () => (acc.push(x), countdown(acc, x-1)) :
      acc;
  
  trampoline(countdown([], 4))
  // [ 4, 3, 2, 1, 0 ]
  
  trampoline(countdown([], -1))
  // []

  Type parameters

  • T

  Parameters

  • f: T | Fn0<T | Fn0<T>>

    function

  Returns T