On Sep 17, 2012, at 11:27 AM, Ryan Culpepper wrote: > On 09/17/2012 02:20 PM, John Clements wrote: >> >> On Sep 16, 2012, at 5:48 PM, Ryan Culpepper wrote: >> >>> See 'define-template-metafunction' in syntax/parse/experimental/template. >>> Remember to change the relevant occurrences of 'syntax' to 'template'. >> >> Neat! >> >> I'm guessing, though, that I probably shouldn't release planet packages that >> depend on experimental-mumble… > > I think it's fine if you're prepared to update the package when it changes. > If I do remove syntax/parse/experimental/template, I'll mark it as deprecated > for a release cycle or two first.
I'm still not quite sold. In particular, I have students writing code against this planet package, and I've just recently had a situation where a student wanted to run his old code, and I was happy to be able to tell him to qualify his planet reference so as to avoid having to update his code; relying on a feature that later disappears reduces the chance that students will be able to run their code as-is three years from now. I really don't mean to be persnickety, here: another motivation is that I've already bitten the bullet and written the code that doesn't require define-template-metafunction :). John > > Ryan > > >>> On 09/16/2012 08:31 PM, John Clements wrote: >>>> I want to apply a transformation to a nested pattern element. >>>> >>>> To start with, suppose I have a (kind of useless) with-handlers that looks >>>> like this: >>>> >>>> (with-syntax >>>> ([((arg ...) ...) >>>> #`((clause.input ...) ...)]) >>>> et-cetera) >>>> >>>> That is, I've basically just renamed "clause.input" to "arg". >>>> >>>> But now, I want to perform some transformation on the elements. I'd like >>>> to write this: >>>> >>>> (with-syntax >>>> ([((arg ...) ...) >>>> #`((#,(transform #'clause.input) ...) ...)]) >>>> et-cetera) >>>> >>>> .. but this fails, with the error "new-style-signals.rkt:42:30: syntax: >>>> missing ellipsis with pattern variable in template in: clause.input" >>>> >>>> I can certainly work around this, by abandoning the pattern-matching >>>> slickness and just using a bunch of syntax->lists, but it seems like there >>>> must be a nicer way. Am I missing some nifty trick? >>>> >>>> John >>>> >>>> >>>> >>>> >>>> _________________________ >>>> Racket Developers list: >>>> http://lists.racket-lang.org/dev >>>> >>> >> >
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