continuation-passing style

[[Continuation]]-passing style is a style of (Lisp) programming where control flow continues through the passing of functions.

Typically, it looks like this:

#lang racket

(define (add x y k)
  (k (+ x y)))

This would pass the control flow to k. The idea, then, is that your whole program threads through in this manner. The interpreter would define the first lambda and pass it in as k.

#lang racket

(define (add x y k)
  (k (+ x y)))

(add 1 2 (lambda (n) (+ 3 n)))

The interpreter could thus use continuations for all calls.

[[Scheme]] in particular is implemented in such a way that you can use the current continuation directly by calling call/cc, or “call with current continuation.”