Dmitry Bogatov <kact...@gnu.org> writes:
> It seems following is invalid:
>
> (let ((a 2))
> (define (foo x) (+ a x)))
>
> I prefer to reduce scope of variable as much as possible, so
> I find this restriction unconvinent. Is is part of standard or technical
> limitation? Is it any workaround?
>
> Please, keep in CC, I am not subscribed.
>
> --
> Best regards, Dmitry Bogatov <kact...@gnu.org>,
> Free Software supporter and netiquette guardian.
> git clone git://kaction.name/rc-files.git --depth 1
> GPG: 54B7F00D
> Html mail and proprietary format attachments are forwarded to /dev/null.
No Scheme standard so far has supported such a thing, and neither Guile.
It would be neat, I had the idea too (it would allow re-use of the
semantics of `begin' and thus be coherent/orthogonal in a way), but I
think it's a non-trivial change, probably both to the implementation of
Guile and the semantics for `let' that have been well-understood ever
since very old Lisps: that `let' is a thin wrapper around a call to an
in-place `lambda'.
(let ((a x)
(b y))
...)
is just
((lambda (a b)
...)
x y)
in pretty much any Lisp.
Note that you can do
(define foo
(let ((a 2))
(lambda (x) (+ a x))))
and if you want to define multiple things that use that `a' binding, you
could use `define-values', but Guile doesn't have that yet (there's a
hacky in-Scheme definition in R7RS-small if you want something quick):
(define-values (foo bar)
(let ((a 2))
(values
(lambda (x) (+ a x))
(lambda (y) (* a y)))))
Taylan
