concat with separators ?

concat with separators ?

[Jean-Christophe Helary]

I just realized today that concat did not come with optional separators (unlike mapconcat). Is there a reason for that ?

Jean-Christophe 

Re: concat with separators ?

[Kaushal Modi]

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On Wed, May 24, 2017 at 10:19 AM Jean-Christophe Helary <
jean.christophe.helary@gmail.com> wrote:

> I just realized today that concat did not come with optional separators
> (unlike mapconcat). Is there a reason for that ?
>

I just using mapconcat when I feel that need:

Example:

(mapconcat #'identity '("a" "b" "c") "|")  => "a|b|c"
-- 

Kaushal Modi

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Re: concat with separators ?

[Clément Pit-Claudel]

On 2017-05-24 10:21, Kaushal Modi wrote:
> On Wed, May 24, 2017 at 10:19 AM Jean-Christophe Helary <jean.christophe.helary@gmail.com <mailto:jean.christophe.helary@gmail.com>> wrote:
> 
>     I just realized today that concat did not come with optional separators (unlike mapconcat). Is there a reason for that ?
> 
> 
> I just using mapconcat when I feel that need:
> 
> Example:
> 
> (mapconcat #'identity '("a" "b" "c") "|")  => "a|b|c"

That's roughly the definition of string-join in subr-x:

(defsubst string-join (strings &optional separator)
  "Join all STRINGS using SEPARATOR."
  (mapconcat 'identity strings separator))

Re: concat with separators ?

[Jean-Christophe Helary]

> On May 24, 2017, at 23:34, Clément Pit-Claudel <cpitclaudel@gmail.com> wrote:
> 
>> I just realized today that concat did not come with optional separators (unlike mapconcat). Is there a reason for that ?
>> 
>>> I just using mapconcat when I feel that need:
>>> 
>>> Example:
>>> 
>>> (mapconcat #'identity '("a" "b" "c") "|")  => "a|b|c"
>> 
>> That's roughly the definition of string-join in subr-x:
>> 
>> (defsubst string-join (strings &optional separator)
>>  "Join all STRINGS using SEPARATOR."
>>  (mapconcat 'identity strings separator))

Would it be acceptable to provide separators to concat or is it preferable to use string-join instead?

Jean-Christophe 

Re: concat with separators ?

[Tino Calancha]

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On Sun, 28 May 2017, Jean-Christophe Helary wrote:

>
>> On May 24, 2017, at 23:34, Clément Pit-Claudel <cpitclaudel@gmail.com> wrote:
>>
>>> I just realized today that concat did not come with optional separators (unlike mapconcat). Is there a reason for that ?
>>>
>>>> I just using mapconcat when I feel that need:
>>>>
>>>> Example:
>>>>
>>>> (mapconcat #'identity '("a" "b" "c") "|")  => "a|b|c"
>>>
>>> That's roughly the definition of string-join in subr-x:
>>>
>>> (defsubst string-join (strings &optional separator)
>>>  "Join all STRINGS using SEPARATOR."
>>>  (mapconcat 'identity strings separator))
>
> Would it be acceptable to provide separators to concat or is it preferable to use string-join instead?
The latter.
Func. `concat' accepts and arbitrary number of sequences (not a list of
sequences as `string-join').

Re: concat with separators ?

[Jean-Christophe Helary]

> On May 28, 2017, at 19:52, Tino Calancha <tino.calancha@gmail.com> wrote:
> 
>>>> That's roughly the definition of string-join in subr-x:
>>>> 
>>>> (defsubst string-join (strings &optional separator)
>>>> "Join all STRINGS using SEPARATOR."
>>>> (mapconcat 'identity strings separator))
>> 
>> Would it be acceptable to provide separators to concat or is it preferable to use string-join instead?

> The latter.
> Func. `concat' accepts any arbitrary number of sequences (not a list of
> sequences as `string-join').

I know that, but subr-x is experimental (hence not documented in the manual) and having to use mapconcat just to add a separator seems not practical.

Jean-Christophe 

Re: concat with separators ?

[Tino Calancha]

On Sun, 28 May 2017, Jean-Christophe Helary wrote:

>
>> On May 28, 2017, at 19:52, Tino Calancha <tino.calancha@gmail.com> wrote:
>>
>>>>> That's roughly the definition of string-join in subr-x:
>>>>>
>>>>> (defsubst string-join (strings &optional separator)
>>>>> "Join all STRINGS using SEPARATOR."
>>>>> (mapconcat 'identity strings separator))
>>>
>>> Would it be acceptable to provide separators to concat or is it preferable to use string-join instead?
>
>> The latter.
>> Func. `concat' accepts any arbitrary number of sequences (not a list of
>> sequences as `string-join').
>
> I know that, but subr-x is experimental (hence not documented in the manual) and having to use mapconcat just to add a separator seems not practical.
I wouldn't worry too much about `string-join' not being in the manual. 
It's going to keep there.  If it's convenient for you feel free to use it.
Many people here like to use stuff from subr-x.el.

Or you can create in your package a `foo-string-join' (foo being your 
package prefix).  Once you write your package manual, this function will 
be documented in the Emacs manual as well.

We cannot modify `concat' with a new argument `separator' without breaking 
existent code.
You can pass the separator between strings:

(concat "foo" ":" "bar" ":" "qux")
=> "foo:bar:qux"

Or use format:
(format "%s:%s:%s" "foo" "bar" "qux")
=> "foo:bar:qux"