(message (Hello 'Paul)
(you :wrote :on '(09 Dec 2006 01:01:14 -0800))
(
PR> If Common Lisp didn't have lexically scoped variables (most Lisp
PR> dialects before Scheme didn't have them) then it would be very
PR> difficult to add that with macros.
i think there's some way to hack that. for example, make defun a macro that
will collect all lexically scoped variable and mangle them. for example:
(defun foo () (let ((i 1)) (print i)))
will be transformed to
(defun foo () (let ((i_foo 1)) (print i_foo)))
(or just some random suffix). this way variables in different functions will
never collide. maybe there's a catch somewhere, but that should look very
close to lexical variables.
PR> Do you seriously think lexical scoping is the last word in language
PR> features and that there's now nothing left in other languages that
PR> can't straightforwardly be done in CL? Hint:
PR> call-with-current-continuation (also known as call/cc).
there's nothing impossible :)
we even have a lib for nondeterministic calculations -- Screamer, that's
much much more cool than that call/cc..
(defun pythagorean-triples (n)
(all-values
(let ((a (an-integer-between 1 n))
(b (an-integer-between 1 n))
(c (an-integer-between 1 n)))
(unless (= (+ (* a a) (* b b)) (* c c)) (fail))
(list a b c))))
you define ranges for variables, define constraints (in a form very close to
normal lisp code) and then just say -- all-values, or solutions (first thing
that satisfies constaints).
)
(With-best-regards '(Alex Mizrahi) :aka 'killer_storm)
"People who lust for the Feel of keys on their fingertips (c) Inity")
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