(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.