That's a bug. A pattern variable should always be bound to a syntax object.
Ryan
On 09/21/2011 03:39 PM, Casey Klein wrote:
I'm confused by the behavior of syntax/parse pattern variables that
come after dots. Sometimes they're bound to lists and sometimes to
syntax objects.
For example, in the following example, the variable `after-ones' gets
bound to a list:
#lang racket/base
(require (for-syntax racket/base))
(begin
(require (for-syntax syntax/parse))
(define-syntax (m stx)
(syntax-parse stx
[(_ 1 ... . after-ones:expr)
(if (list? #'after-ones)
#''list
#''not-list)]))
(m 1 1 2 1 2 3)) ; 'list
but it gets bound to a syntax object if I drop the variable's `expr'
syntax-class.
That is, unless you're using scribble/eval, in which case dropping the
syntax-class does not change the behavior:
#lang scribble/manual
@(require scribble/eval)
@(parameterize ([current-eval (make-base-eval)])
(interaction-eval (require (for-syntax racket/base)))
(interaction (begin
(require (for-syntax syntax/parse))
(define-syntax (m stx)
(syntax-parse stx
[(_ 1 ... . after-ones:expr)
(if (list? #'after-ones)
#''list
#''not-list)]))
(m 1 1 2 1 2 3))))
What's going on?
_________________________________________________
For list-related administrative tasks:
http://lists.racket-lang.org/listinfo/dev
_________________________________________________
For list-related administrative tasks:
http://lists.racket-lang.org/listinfo/dev
