Yes in that case this stands on it's own! /Stefan On Mon, Oct 22, 2012 at 9:11 PM, Mikael Djurfeldt <mik...@djurfeldt.com>wrote:
> On Mon, Oct 22, 2012 at 8:31 PM, Stefan Israelsson Tampe > <stefan.ita...@gmail.com> wrote: > >> Comments? Can I add syntax-toplevel? to psyntax.scm and (system > >> syntax)? > > [...] > > I can answer with some kind of suggestion here. > > > > in (system syntax) there is syntax-local-binding which you can use for > > example as > > > > > > (define-syntax f > > (lambda (x) > > (syntax-case x () > > ((_ x) > > (call-with-values (lambda () (syntax-local-binding #'x)) > > (lambda (x y) (pk x) (pk y))) #'#t)))) > > > > Then, > > > > scheme@(guile-user) [1]> (f +) > > > > ;;; (global) > > > > ;;; ((+ guile-user)) > > > > And, > > > > scheme@(guile-user) [1]> (let ((s 1)) (f s)) > > > > ;;; (lexical) > > > > ;;; (s-490) > > > > (let ((s 1)) (define-syntax g (lambda (x) #'#f)) (f g)) > > > > ;;; (displaced-lexical) > > > > ;;; (#f) > > > > I'm not sure what exactly syntax-toplevel? does, but can you base it on > > syntax-local-binding? > > And if not is it possible to change syntax-local-binding so that you can > use > > it? > > Thanks, Stefan. > > (syntax-toplevel?) expands to #t if occurs in a context (position in > the code if you prefer) where a (define x #f) would create/set! a > global binding for x. It expands to #f otherwise. > > I had a look at syntax-local-binding, but decided that > syntax-toplevel? was needed since the latter is not trying to > determine the nature of an existing binding but rather the nature of > the context. Of course oncould probe the context by first creating a > new binding (with some random name) and then use syntax-local-binding > to determine the nature of the context by looking at the new binding, > but that seems somewhat invasive. :-) >
