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* newbie questions: why doesn't ((lambda (x) (x 2)) (lambda (n) (+ n 3))) work in elisp?
@ 2008-05-30 17:03 Tahsin Alam
  2008-05-31  6:41 ` Thien-Thi Nguyen
       [not found] ` <mailman.12481.1212216300.18990.help-gnu-emacs@gnu.org>
  0 siblings, 2 replies; 5+ messages in thread
From: Tahsin Alam @ 2008-05-30 17:03 UTC (permalink / raw)
  To: help-gnu-emacs

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As the subject says - why does the following expression give error when I try
to evaluate it in the *scratch* buffer?

((lambda (x) (x 2)) (lambda (n) (+ n 3)))


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^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: newbie questions: why doesn't ((lambda (x) (x 2)) (lambda (n) (+ n 3))) work in elisp?
       [not found] <mailman.12463.1212181801.18990.help-gnu-emacs@gnu.org>
@ 2008-05-30 21:27 ` Joost Diepenmaat
  2008-05-30 21:33   ` Joost Diepenmaat
  0 siblings, 1 reply; 5+ messages in thread
From: Joost Diepenmaat @ 2008-05-30 21:27 UTC (permalink / raw)
  To: help-gnu-emacs

Tahsin Alam <tahsin.alam@db.com> writes:

> As the subject says - why does the following expression give error when I try to evaluate it in the *scratch* buffer?
>
> ((lambda (x) (x 2)) (lambda (n) (+ n 3)))

Because ((some call evaluating to a function)) isn't valid in emacs
lisp, which also means

(lambda (x) (x 2))

has no real meaning in elisp (it does in scheme, but not in elisp or
common lisp, because elisp and cl have separate namespaces for
functions and variables). You want either

(funcall (lambda (x) (funcall x 2)) (lambda (n) (+ n 3)))

or possibly

(list (lambda (x) (list x 2)) (lambda (n) (+ n 3)))

or some permutation of both.

-- 
Joost Diepenmaat | blog: http://joost.zeekat.nl/ | work: http://zeekat.nl/


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: newbie questions: why doesn't ((lambda (x) (x 2)) (lambda (n) (+ n 3))) work in elisp?
  2008-05-30 21:27 ` newbie questions: why doesn't ((lambda (x) (x 2)) (lambda (n) (+ n 3))) work in elisp? Joost Diepenmaat
@ 2008-05-30 21:33   ` Joost Diepenmaat
  0 siblings, 0 replies; 5+ messages in thread
From: Joost Diepenmaat @ 2008-05-30 21:33 UTC (permalink / raw)
  To: help-gnu-emacs


Joost Diepenmaat <joost@zeekat.nl> writes:
> Tahsin Alam <tahsin.alam@db.com> writes:
>
>> As the subject says - why does the following expression give error when I try to evaluate it in the *scratch* buffer?
>>
>> ((lambda (x) (x 2)) (lambda (n) (+ n 3)))
>
> Because ((some call evaluating to a function)) isn't valid in emacs
> lisp, which also means
>
> (lambda (x) (x 2))

unless, of course, you've got a (defun x (y) ...) somewhere...

> has no real meaning in elisp (it does in scheme, but not in elisp or
> common lisp, because elisp and cl have separate namespaces for
> functions and variables). You want either
>
> (funcall (lambda (x) (funcall x 2)) (lambda (n) (+ n 3)))
>
> or possibly
>
> (list (lambda (x) (list x 2)) (lambda (n) (+ n 3)))
>
> or some permutation of both.

-- 
Joost Diepenmaat | blog: http://joost.zeekat.nl/ | work: http://zeekat.nl/


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: newbie questions: why doesn't ((lambda (x) (x 2)) (lambda (n) (+ n 3))) work in elisp?
  2008-05-30 17:03 Tahsin Alam
@ 2008-05-31  6:41 ` Thien-Thi Nguyen
       [not found] ` <mailman.12481.1212216300.18990.help-gnu-emacs@gnu.org>
  1 sibling, 0 replies; 5+ messages in thread
From: Thien-Thi Nguyen @ 2008-05-31  6:41 UTC (permalink / raw)
  To: Tahsin Alam; +Cc: help-gnu-emacs

⎛⎞ Tahsin Alam <tahsin.alam@db.com>
⎝⎠ Fri, 30 May 2008 13:03:49 -0400

   As the subject says - why does the following expression give
   error when I try to evaluate it in the *scratch* buffer?

   ((lambda (x) (x 2)) (lambda (n) (+ n 3)))

One reason is because Emacs Lisp is not Scheme (sigh).
You can try this, instead:

(funcall (lambda (x) (funcall x 2)) (lambda (n) (+ n 3)))

thi




^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: newbie questions: why doesn't ((lambda (x) (x 2)) (lambda (n) (+ n 3))) work in elisp?
       [not found] ` <mailman.12481.1212216300.18990.help-gnu-emacs@gnu.org>
@ 2008-05-31  8:58   ` Johan Bockgård
  0 siblings, 0 replies; 5+ messages in thread
From: Johan Bockgård @ 2008-05-31  8:58 UTC (permalink / raw)
  To: help-gnu-emacs

Thien-Thi Nguyen <ttn@gnuvola.org> writes:

> ⎛⎞ Tahsin Alam <tahsin.alam@db.com>
> ⎝⎠ Fri, 30 May 2008 13:03:49 -0400
>
>    As the subject says - why does the following expression give
>    error when I try to evaluate it in the *scratch* buffer?
>
>    ((lambda (x) (x 2)) (lambda (n) (+ n 3)))
>
> One reason is because Emacs Lisp is not Scheme (sigh).
> You can try this, instead:
>
> (funcall (lambda (x) (funcall x 2)) (lambda (n) (+ n 3)))

The first funcall is unnecessary.

-- 
Johan Bockgård


^ permalink raw reply	[flat|nested] 5+ messages in thread

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2008-05-30 21:27 ` newbie questions: why doesn't ((lambda (x) (x 2)) (lambda (n) (+ n 3))) work in elisp? Joost Diepenmaat
2008-05-30 21:33   ` Joost Diepenmaat
2008-05-30 17:03 Tahsin Alam
2008-05-31  6:41 ` Thien-Thi Nguyen
     [not found] ` <mailman.12481.1212216300.18990.help-gnu-emacs@gnu.org>
2008-05-31  8:58   ` Johan Bockgård

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