From bf26430df156fa887f9d6f241474a628a3e12d8e Mon Sep 17 00:00:00 2001 From: Jim Pryor Date: Mon, 20 Dec 2010 22:34:31 -0500 Subject: [PATCH] cps tweak Signed-off-by: Jim Pryor --- cps_and_continuation_operators.mdwn | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/cps_and_continuation_operators.mdwn b/cps_and_continuation_operators.mdwn index 0d4eb1df..1ddcf37d 100644 --- a/cps_and_continuation_operators.mdwn +++ b/cps_and_continuation_operators.mdwn @@ -397,6 +397,10 @@ Here is [the answer](/hints/cps_hint_4), but again, first try to figure it out f Delimited control operators =========================== +Here again is the CPS for `callcc`: + + [callcc (\k. body)] = \outk. (\k. [body] outk) (\v localk. outk v) + `callcc` is what's known as an *undelimited control operator*. That is, the continuations `outk` that get bound to our `k`s behave as though they include all the code from the `call/cc ...` out to *and including* the end of the program. Often times it's more useful to use a different pattern, where we instead capture only the code from the invocation of our control operator out to a certain boundary, not including the end of the program. These are called *delimited control operators*. A variety of the latter have been formulated. -- 2.11.0