From: Jim Pryor Date: Tue, 21 Dec 2010 03:34:31 +0000 (-0500) Subject: cps tweak X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=bf26430df156fa887f9d6f241474a628a3e12d8e;hp=d375f5d50a8cb9449932294ee76266cfb0dd36b6;ds=sidebyside cps tweak Signed-off-by: Jim Pryor --- 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.