If you look in the Typed Racket implementation, you'll see lots phase-1 only uses of syntax-parse.
Sam On Sep 24, 2013 3:21 PM, "Nick Sivo" <nicks...@gmail.com> wrote: > Why doesn't syntax/parse just provide everything at phases 0 and 1 > like the module 'sp below: > > (module sp racket/base > (require syntax/parse > (for-syntax syntax/parse)) > (provide (all-from-out syntax/parse) > (for-syntax (all-from-out syntax/parse)))) > > (require 'sp) > > (define-syntax (mylet stx) > (syntax-parse stx > [(_ ([var-id rhs-expr] ...) body ...+) > #'((lambda (var-id ...) body ...) rhs-expr ...)])) > > I've not done as much Racket programming as many of you, but I've yet > to want syntax/parse in only phase 0. > > -Nick > > On Tue, Sep 24, 2013 at 10:21 AM, Laurent <laurent.ors...@gmail.com> > wrote: > > This is a quite common pitfall into which I have myself fallen a few > times, > > and I guess it's not the last time. > > > > How much work would be required to prevent people from falling into it > ever > > again? > > Maybe saying so in the docs at the right place wouldn't hurt, but people > may > > still miss it. > > Maybe making the error message more specific like "Did you forget to > > (require (for-syntax syntax/parse)) ?" ? Or is it too specific? > > Or pushing the idea further (and requiring more work, obviously), > Racket's > > errors could propose a list of packages where the unknown identifier can > be > > found, along with the require phase? Is xref able to do that currently? > > > > Laurent > > > > > > > > On Tue, Sep 24, 2013 at 6:20 PM, Stephen Chang <stch...@ccs.neu.edu> > wrote: > >> > >> You need (require (for-syntax syntax/parse)) because you are using it > >> inside a define-syntax. > >> > >> On Sep 24, 2013 11:56 AM, "Konrad Hinsen" <konrad.hin...@fastmail.net> > >> wrote: > >>> > >>> Hi everyone, > >>> > >>> I am trying to learn about syntax-parse, starting with the introduction > >>> of the "Syntax" documentation. > >>> > >>> Unfortunately, the very first example given for the use of syntax-parse > >>> doesn't work in my Racket installation: > >>> > >>> Welcome to Racket v5.90.0.9. > >>> racket@> (require syntax/parse) > >>> racket@> (define-syntax (mylet stx) > >>> (syntax-parse stx > >>> [(_ ([var-id rhs-expr] ...) body ...+) > >>> #'((lambda (var-id ...) body ...) rhs-expr ...)])) > >>> stdin::277: _: wildcard not allowed as an expression > >>> in: (_ ((var-id rhs-expr) ...) body ...+) > >>> errortrace...: > >>> context...: > >>> try-next > >>> > >>> > /Users/hinsen/Development/racket/pkgs/errortrace-pkgs/errortrace-lib/errortrace/errortrace-lib.rkt:480:4 > >>> > >>> /Users/hinsen/Applications/Racket/collects/racket/private/misc.rkt:87:7 > >>> > >>> I tried replacing the wildcard by "mylet", but that only leads to > another > >>> error > >>> message: > >>> > >>> racket@> (define-syntax (mylet stx) > >>> (syntax-parse stx > >>> [(mylet ([var-id rhs-expr] ...) body ...+) > >>> #'((lambda (var-id ...) body ...) rhs-expr ...)])) > >>> stdin::842: ...: ellipses not allowed as an expression > >>> in: ... > >>> errortrace...: > >>> context...: > >>> try-next > >>> > >>> > /Users/hinsen/Development/racket/pkgs/errortrace-pkgs/errortrace-lib/errortrace/errortrace-lib.rkt:480:4 > >>> > >>> /Users/hinsen/Applications/Racket/collects/racket/private/misc.rkt:87:7 > >>> > >>> Am I doing something wrong here? Or are the examples obsolete? > >>> > >>> Konrad. > >>> ____________________ > >>> Racket Users list: > >>> http://lists.racket-lang.org/users > >> > >> > >> ____________________ > >> Racket Users list: > >> http://lists.racket-lang.org/users > >> > > > > > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users >
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