Re: Predicate for true lists

[Basil L. Contovounesios]

Drew Adams <address@hidden> writes:

>> > As for `cdr` vs CDR.  The all-caps version is a metavariable referring
>> > to something which we happened to call CDR.  E.g.
>> >
>> >     Foo takes the form (CAR . CDR) where CDR is blabla.
>> 
>> Right, but I see no such destructuring/metasyntax in the Elisp manual.
>> Both "(elisp) Cons Cells" and "(elisp) Cons Cell Type", for example,
>> refer directly to the CAR and CDR slots of a cons cell, without first
>> illustrating their structure.  Is that OK?
>
> My answer probably does not reflect an Emacs doc-string or
> manual convention, but here are my 2 cents anyway:
>
> 1. Uppercase: As Stefan said, only when it refers to a
> piece of a pattern.
>
> 2. Lowercase in code font (e.g. what Stefan wrote as `cdr`
> and you wrote as `cdr'): Only when referring to the function.
>
> 3. Lowercase otherwise.  In talking about Lisp, "car" and
> "cdr" are regular English words, just like "first" and "rest".
> They are Lisp jargon words, but they are English nevertheless.

Agreed.

> IOW, there's no reason we should not just talk about the cdr
> of a list, with no special typography used for the word "cdr".

In the manual, yes.  In docstrings, on the other hand, I like that `cdr'
quoting results in a link to that function's documentation.

-- 
Basil