From: Jim Pryor Date: Tue, 21 Dec 2010 03:40:02 +0000 (-0500) Subject: cps tweak X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=9276f153f6bf9a6426e58fddce62288b6ca80b39 cps tweak Signed-off-by: Jim Pryor --- diff --git a/cps_and_continuation_operators.mdwn b/cps_and_continuation_operators.mdwn index 63a40a16..bed466e1 100644 --- a/cps_and_continuation_operators.mdwn +++ b/cps_and_continuation_operators.mdwn @@ -403,9 +403,7 @@ Here again is the CPS for `callcc`: `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. - -The most well-behaved from where we're coming from is the pair `reset` and `shift`. `reset` sets the boundary, and `shift` binds the continuation from the position where it's invoked out to that boundary. +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 these have been formulated. The most well-behaved from where we're coming from is the pair `reset` and `shift`. `reset` sets the boundary, and `shift` binds the continuation from the position where it's invoked out to that boundary. It works like this: