From: Tassilo Horn <tsdh@gnu.org>
To: 16238@debbugs.gnu.org
Subject: bug#16238: 24.3.50; pcase docs (and possibly pcase) wrong
Date: Tue, 24 Dec 2013 10:37:06 +0100 [thread overview]
Message-ID: <87ha9yvbct.fsf@thinkpad.tsdh.org> (raw)
In-Reply-To: <87ob46vcfl.fsf@thinkpad.tsdh.org> (Tassilo Horn's message of "Tue, 24 Dec 2013 10:13:50 +0100")
Tassilo Horn <tsdh@gnu.org> writes:
> ELISP> (evaluate '(fn x (add 1 x)) nil)
> (lambda
> (val)
> (evaluate body
> (cons
> (cons arg val)
> env)))
>
> But shouldn't `arg' be substituted with 'x and `body' with '(add 1 x)?
It seems the `lambda' is the problem that prevents substitution of arg
and body. By doing some kinda strange quoting I can get it right, but
IMHO that shouldn't be needed:
--8<---------------cut here---------------start------------->8---
(defun evaluate (exp env)
(pcase exp
(`(add ,x ,y) (+ (evaluate x env) (evaluate y env)))
(`(call ,fun ,arg) (funcall (evaluate fun env) (evaluate arg env)))
(`(fn ,arg ,body) `(lambda (val)
(evaluate ',body (cons (cons ',arg val) env))))
((pred numberp) exp)
((pred symbolp) (cdr (assq exp env)))
(_ (error "Unknown expression %S" exp))))
--8<---------------cut here---------------end--------------->8---
ELISP> (evaluate '(fn x (add 1 x)) nil)
(lambda
(val)
(evaluate
'(add 1 x)
(cons
(cons 'x val)
env)))
ELISP> (evaluate '(call (fn x (add 1 x)) 3) nil)
4 (#o4, #x4, ?\C-d)
Bye,
Tassilo
next prev parent reply other threads:[~2013-12-24 9:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-24 9:13 bug#16238: 24.3.50; pcase docs (and possibly pcase) wrong Tassilo Horn
2013-12-24 9:37 ` Tassilo Horn [this message]
2013-12-24 9:55 ` Michael Heerdegen
2013-12-24 14:53 ` Stefan Monnier
2013-12-24 15:34 ` Tassilo Horn
2013-12-24 20:13 ` Glenn Morris
2013-12-25 9:15 ` Tassilo Horn
2013-12-25 20:04 ` Tassilo Horn
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