print out all members of a list

print out all members of a list

[ken]

(car '("one" "two" "three"))

prints out "one" ... the first of the list.  How to print out all
elements of the list (in order and with the double quotes around them?
I'm actually looking just to substitute something for "car" and not
write an entire function.  Or is there no such thing?

Thanks much.

Re: print out all members of a list

[Marc Mientki]

Am 28.02.2011 16:20, schrieb ken:
> (car '("one" "two" "three"))

(mapcar 'print '("one" "two" "three"))

regards
Marc

Re: print out all members of a list

[Teemu Likonen]

* 2011-02-28 10:20 (-0500), ken wrote:

> (car '("one" "two" "three"))
>
> prints out "one" ... the first of the list. How to print out all
> elements of the list (in order and with the double quotes around them?
> I'm actually looking just to substitute something for "car" and not
> write an entire function. Or is there no such thing?

CAR doesn't print anything, it _returns_ a value. I'm not sure what you
mean, maybe this:

    (identity '("one" "two" "three"))

IDENTITY just returns its argument. If you need some kind of
pretty-printing you could try PP function.

Re: print out all members of a list

[ken]

On 02/28/2011 10:20 AM ken wrote:
> (car '("one" "two" "three"))
> 
> prints out "one" ... the first of the list.  How to print out all
> elements of the list (in order and with the double quotes around them?
> I'm actually looking just to substitute something for "car" and not
> write an entire function.  Or is there no such thing?
> 
> Thanks much.
> 

I've been criticized for my elisp terminology-- and properly so--, so
let me rephrase:

(car '("one" "two" "three"))

returns a string consisting of the first element (?) of the list.  Is
there an elisp function which either (1) returns one string for each
element of the list or (2) returns one string containing all elements of
the list?

E.g.:

(1) "one" "two" "three"

or

(2) "onetwothree"

preferably (1).


Thanks again.


P.S. It seems strange that elisp has so many ways to manipulate lists,
but doesn't seem to have this very simple functionality.

Re: print out all members of a list

[Thierry Volpiatto]

ken <gebser@mousecar.com> writes:

> On 02/28/2011 10:20 AM ken wrote:
>> (car '("one" "two" "three"))
>> 
>> prints out "one" ... the first of the list.  How to print out all
>> elements of the list (in order and with the double quotes around them?
>> I'm actually looking just to substitute something for "car" and not
>> write an entire function.  Or is there no such thing?
>> 
>> Thanks much.
>> 
>
> I've been criticized for my elisp terminology-- and properly so--, so
> let me rephrase:
>
> (car '("one" "two" "three"))
>
> returns a string consisting of the first element (?) of the list.  Is
> there an elisp function which either (1) returns one string for each
> element of the list or (2) returns one string containing all elements of
> the list?
>
> E.g.:
>
> (1) "one" "two" "three"
(loop for i in '("one" "two" "three") do (princ (concat "\"" i "\"" " ")))

> or
>
> (2) "onetwothree"
(mapconcat 'identity '("one" "two" "three") " ")
==>"one two three"

> preferably (1).
>
>
> Thanks again.
>
>
> P.S. It seems strange that elisp has so many ways to manipulate lists,
> but doesn't seem to have this very simple functionality.
Because "one" "two" "three" is unusable in code if not in a container.
(i.e it is three differents objects, but not one)

-- 
A+ Thierry
Get my Gnupg key:
gpg --keyserver pgp.mit.edu --recv-keys 59F29997 

Re: print out all members of a list

[PJ Weisberg]

On 2/28/11, ken <gebser@mousecar.com> wrote:
> On 02/28/2011 10:20 AM ken wrote:
>> (car '("one" "two" "three"))
>>
>> prints out "one" ... the first of the list.  How to print out all
>> elements of the list (in order and with the double quotes around them?
>> I'm actually looking just to substitute something for "car" and not
>> write an entire function.  Or is there no such thing?
>>
>> Thanks much.
>>
>
> I've been criticized for my elisp terminology-- and properly so--, so
> let me rephrase:
>
> (car '("one" "two" "three"))
>
> returns a string consisting of the first element (?) of the list.  Is
> there an elisp function which either (1) returns one string for each
> element of the list or (2) returns one string containing all elements of
> the list?
>
> E.g.:
>
> (1) "one" "two" "three"
>
> or
>
> (2) "onetwothree"
>
> preferably (1).

I'm not sure what (1) would actually *mean*, since a list of three
strings is what you already have, but if you did want to print each of
them out, then perhaps something like

(mapc 'insert '("one" "two" "three"))

-PJ

Re: print out all members of a list

[Pascal J. Bourguignon]

ken <gebser@mousecar.com> writes:

> On 02/28/2011 10:20 AM ken wrote:
>> (car '("one" "two" "three"))
>> 
>> prints out "one" ... the first of the list.  How to print out all
>> elements of the list (in order and with the double quotes around them?
>> I'm actually looking just to substitute something for "car" and not
>> write an entire function.  Or is there no such thing?
>> 
>> Thanks much.
>> 
>
> I've been criticized for my elisp terminology-- and properly so--, so
> let me rephrase:
>
> (car '("one" "two" "three"))
>
> returns a string consisting of the first element (?) of the list.  Is
> there an elisp function which either (1) returns one string for each
> element of the list or

Not in emacs lisp, since emacs lisp function can return only ONE result.
They cannot return several results.

Even in Common Lisp which can return several results, there is an
implementation defined on the maximum number of results a function can
return (which must be at least 20, but can also be at most 20 even if
it's often bigger) so you cannot in general return one result per
element of a list, since lists are not limited in length apart from the
memory available.


> (2) returns one string containing all elements of
> the list?

What's wrong with the list itself?  

It already contains all the elements of the list,
and if they're strings as your list seems to contain, it already
contains all the elements of the list (itself) as strings.

In anycase, if you don't mind the parentheses, you can get the list
represented as a string with:

    (let ((list '("one" "two" "tree")))
      (prin1-to-string list))

    --> "(\"one\" \"two\" \"tree\")"


You can also trivially remove the parentheses:

    (let ((list '("one" "two" "tree")))
      (substring (prin1-to-string list) 1 -1))

    --> "\"one\" \"two\" \"tree\""


Now, if the elements of the list are not strings, and you want them to
be strings, you can do so with:

    (let ((list '(one 2 [t h r e e])))
      (mapcar (function prin1-to-string) list))

    --> ("one" "2" "[t h r e e]")
   

and if you still insist to have the result as a single string:

    (let ((list '(one 2 [t h r e e])))
      (substring (prin1-to-string (mapcar (function prin1-to-string) list)) 1 -1))

    --> "\"one\" \"2\" \"[t h r e e]\""

But I repeat, there's little point in converting lists into strings,
since it's so much easier to process data when it's structured into
lists, than when it's mere characters in a string.


> P.S. It seems strange that elisp has so many ways to manipulate lists,
> but doesn't seem to have this very simple functionality.

Yes.  Think about it!


-- 
__Pascal Bourguignon__                     http://www.informatimago.com/
A bad day in () is better than a good day in {}.

Re: print out all members of a list

[Andreas Röhler]

Am 28.02.2011 16:20, schrieb ken:
> (car '("one" "two" "three"))
>
> prints out "one" ... the first of the list.  How to print out all
> elements of the list (in order and with the double quotes around them?
> I'm actually looking just to substitute something for "car" and not
> write an entire function.  Or is there no such thing?
>
> Thanks much.
>
>


Hi,

I like `dolist'

eval this


(let ((my-list (list "one" "two" "three")))
     (dolist (elem my-list)
   (insert (concat "\nHere I am!: " elem))))


HTH


Andreas

--
https://code.launchpad.net/~a-roehler/python-mode/python-mode-components
https://code.launchpad.net/s-x-emacs-werkstatt/

Re: print out all members of a list

[Andreas Röhler]

Am 28.02.2011 16:20, schrieb ken:
> (car '("one" "two" "three"))
>
> prints out "one" ... the first of the list.  How to print out all
> elements of the list (in order and with the double quotes around them?
> I'm actually looking just to substitute something for "car" and not
> write an entire function.  Or is there no such thing?
>
> Thanks much.
>
>

and still a form delivering with doublequotes...

(let ((my-list (list "one" "two" "three")))
     (dolist (elem my-list)
   (insert (format "\n\"%s\"" elem))))

Re: print out all members of a list

[Pascal J. Bourguignon]

Andreas Röhler <andreas.roehler@easy-emacs.de> writes:

> Am 28.02.2011 16:20, schrieb ken:
>> (car '("one" "two" "three"))
>>
>> prints out "one" ... the first of the list.  How to print out all
>> elements of the list (in order and with the double quotes around them?
>> I'm actually looking just to substitute something for "car" and not
>> write an entire function.  Or is there no such thing?
>>
>> Thanks much.
>>
>>
>
> and still a form delivering with doublequotes...
>
> (let ((my-list (list "one" "two" "three")))
>     (dolist (elem my-list)
>   (insert (format "\n\"%s\"" elem))))

Why do you write broken code?

    (let ((my-list (list "o\"n\"e" "t\"wo" "th\\\"ree")))
       (dolist (elem my-list)
          (insert (format "\n\"%s\"" elem))))

    "o"n"e"
    "t"wo"
    "th\"ree"


Is it not easier to write code that works?

    (let ((my-list (list "o\"n\"e" "t\"wo" "th\\\"ree")))
       (dolist (elem my-list)
          (insert (format "\n%s" (prin1-to-string elem)))))

    "o\"n\"e"
    "t\"wo"
    "th\\\"ree"


-- 
__Pascal Bourguignon__                     http://www.informatimago.com/
A bad day in () is better than a good day in {}.

Re: print out all members of a list

[Stefan Monnier]

>           (insert (format "\n%s" (prin1-to-string elem)))))

You meant

        (insert (format "\n%S elem))))

right?


        Stefan

Re: print out all members of a list

[Le Wang]

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prin1-to-string knows how to quote strings properly ... got it.

On Tue, Mar 1, 2011 at 9:10 PM, Pascal J. Bourguignon <pjb@informatimago.com
> wrote:

> Why do you write broken code?
>

...


> Is it not easier to write code that works?


But maybe we don't have to talk like cthun to make our points?

-- 
Le

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Re: print out all members of a list

[Richard Riley]

"Pascal J. Bourguignon" <pjb@informatimago.com> writes:

> Andreas Röhler <andreas.roehler@easy-emacs.de> writes:
>
>> Am 28.02.2011 16:20, schrieb ken:
>>> (car '("one" "two" "three"))
>>>
>>> prints out "one" ... the first of the list.  How to print out all
>>> elements of the list (in order and with the double quotes around them?
>>> I'm actually looking just to substitute something for "car" and not
>>> write an entire function.  Or is there no such thing?
>>>
>>> Thanks much.
>>>
>>>
>>
>> and still a form delivering with doublequotes...
>>
>> (let ((my-list (list "one" "two" "three")))
>>     (dolist (elem my-list)
>>   (insert (format "\n\"%s\"" elem))))
>
> Why do you write broken code?

I'm intrigued. Do you get a bonus point for every time you are rude and
condescending to people looking for help or are patiently helping
others?

Re: print out all members of a list

[Andreas Röhler]

Am 01.03.2011 14:10, schrieb Pascal J. Bourguignon:
> Andreas Röhler<andreas.roehler@easy-emacs.de>  writes:
>
>> Am 28.02.2011 16:20, schrieb ken:
>>> (car '("one" "two" "three"))
>>>
>>> prints out "one" ... the first of the list.  How to print out all
>>> elements of the list (in order and with the double quotes around them?
>>> I'm actually looking just to substitute something for "car" and not
>>> write an entire function.  Or is there no such thing?
>>>
>>> Thanks much.
>>>
>>>
>>
>> and still a form delivering with doublequotes...
>>
>> (let ((my-list (list "one" "two" "three")))
>>      (dolist (elem my-list)
>>    (insert (format "\n\"%s\"" elem))))
>
> Why do you write broken code?
>
>      (let ((my-list (list "o\"n\"e" "t\"wo" "th\\\"ree")))
>         (dolist (elem my-list)
>            (insert (format "\n\"%s\"" elem))))
>
>      "o"n"e"
>      "t"wo"
>      "th\"ree"
>
>
> Is it not easier to write code that works?
>
>      (let ((my-list (list "o\"n\"e" "t\"wo" "th\\\"ree")))
>         (dolist (elem my-list)
>            (insert (format "\n%s" (prin1-to-string elem)))))
>
>      "o\"n\"e"
>      "t\"wo"
>      "th\\\"ree"
>
>

Ok, thanks, interesting point.

 From there `concat' read better for me

(let ((my-list (list "o\"n\"e" "t\"wo" "th\\\"ree")))
        (dolist (elem my-list)
           (insert (concat "\n" (prin1-to-string elem)))))

(?) :-)