On Sat, Jan 7, 2012 at 1:05 AM, Andy Wingo
<address@hidden> wrote:
On Mon 05 Dec 2011 19:12, Stefan Israelsson Tampe <
address@hidden> writes:
> (define-syntax info
> (lambda (x)
> (syntax-case x ()
> ((_ x)
> (pk (syntax-binding-info (syntax->datum #'x)))
> #'#f))))
on datums. Also, what should the type of the return value be? Racket
implies that it should be a procedure, no?
syntax-binding-info just returns the binding information used at a lookup in psyntax for an identifier
but it would be better if it returns a lookup procedure that applied to a syntax object gives the lookuped
information assuming that psyntax is not mutating. using this primitive we can design a syntax-local-value
according to racket
e.g.
(syntax-local-value id-stx [failure-thunk intdef-ctx]) -> any
id-stx : syntax?
failure-thunk : (or/c (-> any) #f) = #f
intdef-ctx : (or/c internal-definition-context? #f) = #f
This should return the value of the macro binding that can be anything and if it's not a macro
eval failure thunk or return #f if not supplied. Also intef-ctx could in our case be then lookup-function
returned by a call to syntax-binding-info in order to mimic the racket logic. To note is that in syntax-parse
syntax classes are defined as a macro with a struct value instead of a transformer. Also to not is that in racket they have special renamer macros that interacts with this function in such a way that the syntax-local-value of a renamer macro is following the renamer and calls this function again on the renamer value
automagically. It should be noted that renamer macros is needed to make syntax-parse clean in that you long descriptive names for the syntax classes and it is assumed that you rename them when using the actual syntax parse.
> and calling this in an example lead to
> (let-syntax ((a (lambda (x) #'#f)))
> (info a))
Does it work on toplevel macros as well?
Yes!