Hi list,
Attached is a patch that implements a new accessor,
syntax-local-binding. It's like syntax-local-value, but can also
determine if an identifier is a pattern var or a normal lexical.
> (define-syntax local-binding
(lambda (x)
(syntax-case x ()
((_ id) (identifier? #'id)
(call-with-values (lambda () (syntax-local-binding #'id))
(lambda (x y)
(with-syntax ((type (datum->syntax #'here x)))
#''type)))))))
> (let-syntax ((x (lambda (x) 10))) (local-binding x))
$3 = local-macro
> (syntax-case #'(foo) () ((id) (local-binding id)))
$4 = pattern-variable
> (let ((x 10)) (local-binding x))
$5 = lexical
It returns two values. The first is a symbol, either `local-macro',
`lexical', or `pattern-variable'. The second is specific to the type.
For local-macro it is the transformer binding. For lexical it is the
gensym name of the lexical. For pattern variables, it is something
opaque that identifies that pattern var.
Inspired by a patch by Stefan Israelsson Tampe.
I'm going to try to implement the-environment with this. We'll see how
it goes!
Andy
--
http://wingolog.org/
