Names to defun, defvar, defconst

Names to defun, defvar, defconst

[uzibalqa]

Names to defun, defvar, and defconst, can include numbers (digits).  Right?

Re: Names to defun, defvar, defconst

[CToID]

> Names to defun, defvar, and defconst, can include numbers (digits).  Right?

As long as there are other non-digit characters in the name, yes.  See the name of the function `1+`.

---

Best,

ID

Re: Names to defun, defvar, defconst

[CToID]

> So these are all valid names
> 
> (defun func1
> 
> (defvar var2
> 
> (defconst const3

Of course they are, I believe these kind of names are valid in almost every single programming language.

---

Best,

ID

Re: Names to defun, defvar, defconst

[uzibalqa]

On Monday, July 1st, 2024 at 8:42 PM, CToID <funk443@yahoo.com.tw> wrote:

> > So these are all valid names
> > 
> > (defun func1
> > 
> > (defvar var2
> > 
> > (defconst const3
> 
> 
> Of course they are, I believe these kind of names are valid in almost every single programming language.
> 
> ---
> 
> Best,
> 
> ID

Latex L3 Programming Layer does not allow numbers, and neither underscores or dashes.

RE: [External] : Re: Names to defun, defvar, defconst

[Drew Adams]

> > So these are all valid names
> > (defun func1
> > (defvar var2
> > (defconst const3
>
> Of course they are, I believe these kind of names
> are valid in almost every single programming language.

You can use pretty much any chars.  Some chars
(e.g. SPC) you need to escape, with \.  E.g.

 (defun \;not\ a\ comment ()
   (message "A function.")
   42)

This prints "A function." and returns 42:

 (\;not\ a\ comment)

You can't use a keyword name (e.g. `:foo')
with defconst.

You _can_ use a keyword name with defvar, but
it doesn't do anything.  Symbols with keyword
names as their `symbol-name' always evaluate
to themselves.

To me, using defvar with a keyword name should
be a BUG, just as it is with defconst.

(defvar :foo 42 "101010") raises no error, and
evaluating `:foo' as a variable returns `:foo',
not 42, because it's a keyword, i.e., a constant.

RE: [External] : Re: Names to defun, defvar, defconst

[Drew Adams]

> You _can_ use a keyword name with defvar, but
> it doesn't do anything.  Symbols with keyword
> names as their `symbol-name' always evaluate
> to themselves.
> 
> To me, using defvar with a keyword name should
> be a BUG, just as it is with defconst.
> 
> (defvar :foo 42 "101010") raises no error, and
> evaluating `:foo' as a variable returns `:foo',
> not 42, because it's a keyword, i.e., a constant.

This bug was fixed in Emacs 28.  Prior to that
what I said was true.  (I still use Emacs 26.)

Re: Names to defun, defvar, defconst

[tpeplt]

uzibalqa <uzibalqa@proton.me> writes:

> Names to defun, defvar, and defconst, can include numbers (digits).  Right?

From:

   (info "(elisp) Symbol Type")

   "A symbol name can contain any characters whatever.  Most symbol names
    are written with letters, digits, and the punctuation characters
    ‘-+=*/’.  Such names require no special punctuation; the characters
    of the name suffice as long as the name does not look like a number.
    (If it does, write a ‘\’ at the beginning of the name to force
    interpretation as a symbol.)  The characters ‘_~!@$%^&:<>{}?’ are less
    often used but also require no special punctuation.  Any other
    characters may be included in a symbol's name by escaping them with a
    backslash.  In contrast to its use in strings, however, a backslash in
    the name of a symbol simply quotes the single character that follows the
    backslash."

There is more in that subsection of the chapter on Lisp data types.

-- 
The lyf so short, the craft so long to lerne.
- Geoffrey Chaucer, The Parliament of Birds.

Re: [External] : Re: Names to defun, defvar, defconst

[Stefan Monnier via Users list for the GNU Emacs text editor]

> You can't use a keyword name (e.g. `:foo') with defconst.

Except for (defconst :foo :foo)


        Stefan

RE: [External] : Re: Names to defun, defvar, defconst

[Drew Adams]

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> > You can't use a keyword name (e.g. `:foo') with defconst.
> 
> Except for (defconst :foo :foo)

Hah!  Indeed.
Thank you. ;-)

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