Computer Dictionary of Information Technology

call-with-current-continuation

(call/cc) A Lisp control function that implements the continuation passing style of programming.

In continuation passing style (CPS), every function f takes an extra final argument k called the "continuation". The continuation is itself a function and represents the rest of the program. Instead of just returning a value in the normal way, f passes it as an argument to k and returns the result of that.

call/cc takes a function f as its argument and calls f, passing it the current continuation k. It thus allows a CPS function to be called in a non-CPS (direct) context.

For example, if the final result is to print the value returned by call/cc then anything passed to k will also be printed.

E.g, in Scheme:

 (define (f k)
	 (k 1)
	 (k 2)
	 3)

 (display (call-with-current-continuation f))

Will display 1.

[Is this correct?]