Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: "A diagram of C23 basic types"
Date: Thu, 03 Apr 2025 14:30:24 -0700
Organization: None to speak of
Lines: 57
Message-ID: <85cydtj5lb.fsf@nosuchdomain.example.com>
References: <87y0wjaysg.fsf@gmail.com> <vsj1m8$1f8h2$1@dont-email.me>
	<vsj2l9$1j0as$1@dont-email.me> <vsjef3$1u4nk$1@dont-email.me>
	<vsjg6t$20pdb$1@dont-email.me> <vsjgjn$1v1n4$1@dont-email.me>
	<vsjk4k$24q5m$1@dont-email.me> <vsjlcp$230a5$1@dont-email.me>
	<vsjmdl$277bk$1@dont-email.me> <VsdHP.1828827$TBhc.1078002@fx16.iad>
	<vskjlo$34st8$1@dont-email.me> <20250402220614.431@kylheku.com>
	<85mscxlqnb.fsf@nosuchdomain.example.com>
	<vsl9sn$3vdjj$2@dont-email.me> <20250403121946.134@kylheku.com>
MIME-Version: 1.0
Content-Type: text/plain
Injection-Date: Thu, 03 Apr 2025 23:30:29 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="658736fab9029f452335cecd036b8387";
	logging-data="1777637"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX19yUDQNZgEsBwOR+gjbNLwu"
User-Agent: Gnus/5.13 (Gnus v5.13)
Cancel-Lock: sha1:OHowEinXMaBUEvBnBZtIup/tKuE=
	sha1:w8z01qBj3waDf8Mnf4sAeBlDiBc=
Bytes: 3504

Kaz Kylheku <643-408-1753@kylheku.com> writes:
[...]
> One programming language that has comma separators is Fortran,
> by the way.  Fortran persisted in providing this feature in spite of
> shooting itself in the foot with ambiguities.
>
> When Fortran was being designed, people were naive in writing
> compilers. They thought that it would simplify things if they
> removed all spaces from the code before lexically scanning it and
> parsing.
>
> Thus "DO I = 1, 10" becomes "DOI=1,10" and "FO I = 1, 10"
> becomes "FOI=1,10"
>
> After that you have to figure out that "DOI=1,10" is the
> header of a DO loop which steps I from 1 to 10,
> whereas "FOI=1,10" assigns 110 to variable FOI.

I don't think that's correct.  My quick experiments with gfortran
indicate that commas are *not* treated as digit separators.

The classic Fortran (or FORTRAN?) error was that:
    DO 10 I = 1,100
(a loop with bounds 1 to 100) was written as:
    DO 10 I = 1.100
(which assigns the value 1.100 to the variable DO10I).

An urban legend says that this error caused the loss of a spacecraft.
In fact the error was caught and corrected before launch.

[...]

> Commas are "fluff punctuators". They could be removed without
> making a difference to the abstract syntax.
>
> Fun fact: early Lisp (when it was called LISP) had commas
> in lists. They were optional. (1, 2, 3) or (1 2 3). Your
> choice.
>
> Comma separation causes problems when arguments can be empty!
>
> In C preprocessing MAC() is actually a macro with one argument,
> which is empty. MAC(,) is a macro with two empty arguments
> and so on.  You cannot write a macro call with zero arguments.
>
> Now, if macros didn't use commas, there wouldn't be a problem
> at all: MAC() -> zero args; MAC(abc) -> one arg;
> MAC(abc 2) -> two args.
> 
> Wow, consistency. And no dangling comma nonsense to deal with in
> complex, variadic macros!

Would MAC("foo" "bar") have one argument or two?

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */