fif function from On Lisp

fif function from On Lisp

[weber]

Hi folks.
For some reason this function from On Lisp doesn't work:

(defun fif (a b &optional c)
  '(lambda (x)
	(if (funcall a x)
		(funcall b x)
		(unless (null c) (funcall c x)))))

I should be able to call it like this:

(mapcar (fif 'zerop '1+ 1-) '(0 1 2 3) => (1 0 1 2)

but i'm probably missing something that is differs from Common Lisp to
Elisp.

Thanks in advance,
weber

Re: fif function from On Lisp

[Johan Bockgård]

weber <hugows@gmail.com> writes:

> Hi folks.
> For some reason this function from On Lisp doesn't work:
>
> (defun fif (a b &optional c)
>   '(lambda (x)
> 	(if (funcall a x)
> 		(funcall b x)
> 		(unless (null c) (funcall c x)))))
>
> I should be able to call it like this:
>
> (mapcar (fif 'zerop '1+ 1-) '(0 1 2 3) => (1 0 1 2)
>
> but i'm probably missing something that is differs from Common Lisp to
> Elisp.

The code above doesn't work in Common Lisp either, but anyway, Emacs
Lisp doesn't have lexical closures (yet).

(info "(elisp) Extent")

-- 
Johan Bockgård

Re: fif function from On Lisp

[weber]

On Mar 4, 9:53 am, bojohan+n...@dd.chalmers.se (Johan Bockgård) wrote:
> weber <hug...@gmail.com> writes:
> > Hi folks.
> > For some reason this function from On Lisp doesn't work:
>
> > (defun fif (a b &optional c)
> >   '(lambda (x)
> >    (if (funcall a x)
> >            (funcall b x)
> >            (unless (null c) (funcall c x)))))
>
> > I should be able to call it like this:
>
> > (mapcar (fif 'zerop '1+ 1-) '(0 1 2 3) => (1 0 1 2)
>
> > but i'm probably missing something that is differs from Common Lisp to
> > Elisp.
>
> The code above doesn't work in Common Lisp either, but anyway, Emacs
> Lisp doesn't have lexical closures (yet).
>
> (info "(elisp) Extent")
>
> --
> Johan Bockgård

Hm. Does that snippet really depends on lexical closures?
I just need that function to expand to this:

(mapcar (lambda (x) (if (funcall 'zerop x) (funcall '1+ x) (funcall
'1- x)))
		'(0 1 2 3))

... maybe I can solve it with a macro then?

-weber

Re: fif function from On Lisp

[weber]

On Mar 4, 10:59 am, weber <hug...@gmail.com> wrote:
> On Mar 4, 9:53 am, bojohan+n...@dd.chalmers.se (Johan Bockgård) wrote:
>
>
>
> > weber <hug...@gmail.com> writes:
> > > Hi folks.
> > > For some reason this function from On Lisp doesn't work:
>
> > > (defun fif (a b &optional c)
> > >   '(lambda (x)
> > >    (if (funcall a x)
> > >            (funcall b x)
> > >            (unless (null c) (funcall c x)))))
>
> > > I should be able to call it like this:
>
> > > (mapcar (fif 'zerop '1+ 1-) '(0 1 2 3) => (1 0 1 2)
>
> > > but i'm probably missing something that is differs from Common Lisp to
> > > Elisp.
>
> > The code above doesn't work in Common Lisp either, but anyway, Emacs
> > Lisp doesn't have lexical closures (yet).
>
> > (info "(elisp) Extent")
>
> > --
> > Johan Bockgård
>
> Hm. Does that snippet really depends on lexical closures?
> I just need that function to expand to this:
>
> (mapcar (lambda (x) (if (funcall 'zerop x) (funcall '1+ x) (funcall
> '1- x)))
>                 '(0 1 2 3))
>
> ... maybe I can solve it with a macro then?
>
> -weber

Ok, i can.
Tks anyway.

(defmacro fif (a b &optional c)
  `(lambda (x)
	 (if (funcall ,a x)
		 (funcall ,b x)
		 (unless (null ,c) (funcall ,c x)))))

-weber

Re: fif function from On Lisp

[weber]

On Mar 4, 11:07 am, weber <hug...@gmail.com> wrote:
> On Mar 4, 10:59 am, weber <hug...@gmail.com> wrote:
>
>
>
> > On Mar 4, 9:53 am, bojohan+n...@dd.chalmers.se (Johan Bockgård) wrote:
>
> > > weber <hug...@gmail.com> writes:
> > > > Hi folks.
> > > > For some reason this function from On Lisp doesn't work:
>
> > > > (defun fif (a b &optional c)
> > > >   '(lambda (x)
> > > >    (if (funcall a x)
> > > >            (funcall b x)
> > > >            (unless (null c) (funcall c x)))))
>
> > > > I should be able to call it like this:
>
> > > > (mapcar (fif 'zerop '1+ 1-) '(0 1 2 3) => (1 0 1 2)
>
> > > > but i'm probably missing something that is differs from Common Lisp to
> > > > Elisp.
>
> > > The code above doesn't work in Common Lisp either, but anyway, Emacs
> > > Lisp doesn't have lexical closures (yet).
>
> > > (info "(elisp) Extent")
>
> > > --
> > > Johan Bockgård
>
> > Hm. Does that snippet really depends on lexical closures?
> > I just need that function to expand to this:
>
> > (mapcar (lambda (x) (if (funcall 'zerop x) (funcall '1+ x) (funcall
> > '1- x)))
> >                 '(0 1 2 3))
>
> > ... maybe I can solve it with a macro then?
>
> > -weber
>
> Ok, i can.
> Tks anyway.
>
> (defmacro fif (a b &optional c)
>   `(lambda (x)
>          (if (funcall ,a x)
>                  (funcall ,b x)
>                  (unless (null ,c) (funcall ,c x)))))
>
> -weber

Just needed to post a correct version:

(defmacro fif (a b &optional c)
  `(lambda (x)
	 (if (funcall ,a x)
		 (funcall ,b x)
		 (if (null ,c) x (funcall ,c x)))))

-weber

Re: fif function from On Lisp

[Mike Mattie]

[-- Attachment #1: Type: text/plain, Size: 924 bytes --]

On Tue, 4 Mar 2008 04:31:19 -0800 (PST)
weber <hugows@gmail.com> wrote:

> Hi folks.
> For some reason this function from On Lisp doesn't work:
> 
> (defun fif (a b &optional c)
>   '(lambda (x)
> 	(if (funcall a x)
> 		(funcall b x)
> 		(unless (null c) (funcall c x)))))
> 
> I should be able to call it like this:
> 
> (mapcar (fif 'zerop '1+ 1-) '(0 1 2 3) => (1 0 1 2)
> 
> but i'm probably missing something that is differs from Common Lisp to
> Elisp.
> 
> Thanks in advance,
> weber

(require 'cl)

(defun plus (x)
  (+ x 1))

(defun minus (x)
  (- x 1))

(defun fif (a b &optional c)
  (lexical-let
    ((a-fn  a)
     (b-fn  b)
     (c-fn  c))

    (lambda (x)
      (if (funcall a-fn x)
        (funcall b-fn x)
        (if (functionp c-fn) (funcall c-fn x))))))

(mapcar (fif 'zerop 'plus 'minus) '(0 1 2 3))  ;; => (1 0 1 2)

This works here.

Cheers,
Mike Mattie

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 189 bytes --]