On 20/05/2015 04:24, Alexis King wrote:
I'm trying to implement a for/stream loop using for/fold/derived that will
return a lazy stream, as would be expected. One way to do this is by using
delimited control, which is what I'm currently trying. If there's an easier
way, let me know, but I'd still like to figure this out as a pedagogical
exercise.
If I understand correctly what you are trying to do, the simplest
solution seems to be a generator.
=================================
#lang racket
(require racket/generator)
(define result-stream
(in-generator
(for ([i (in-naturals 10)])
(yield i))))
(for ([n result-stream])
(printf "~s\n" n))
=================================
This example is a bit pointless because result-stream could just as well
be replaced by (in-naturals 10), but I hope it is clear how this could
be generalized to a meaningful application.
I use this a lot, to the point of considering defining something like
for/sequence to have nicer syntax for this.
Konrad.
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