From: Jim Pryor Date: Tue, 21 Dec 2010 03:39:16 +0000 (-0500) Subject: cps tweak X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=6ad86f1d6d3688a9d2b90e6439905e284037ab4d;hp=5a2706782fc496bfa4274812c21ad8c4e88a60f9 cps tweak Signed-off-by: Jim Pryor --- diff --git a/cps_and_continuation_operators.mdwn b/cps_and_continuation_operators.mdwn index 2aba0c41..63a40a16 100644 --- a/cps_and_continuation_operators.mdwn +++ b/cps_and_continuation_operators.mdwn @@ -401,7 +401,7 @@ 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 into our `k`s include all the code from the `call/cc ...` out to *and including* the end of the program. +`callcc` is what's known as an *undelimited control operator*. That is, the continuations `outk` that get bound into our `k`s include all the code from the `call/cc ...` out to *and including* the end of the program. Calling such a continuation will never return any value to the call site. (See the technique employed in the `delta` example above, with the `(begin (let/cc k2 ...) ...)`, for a work-around.) 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.