Re: Elisp / C inconsistency for reading "1."

[Simon Leinen <simon.leinen@gmail.com>]

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On Sat, Mar 15, 2014 at 5:21 PM, Wolfgang Jenkner <wjenkner@inode.at> wrote:

> But please don't base your opinion on a wrong assumption about Common
> Lisp, see [1],
>
>         Integers can be written as a sequence of digits [...]
>         optionally followed by a decimal point;


Thanks for the reminder!

In case anyone wonders why Common Lisp does it this way: CL has
*READ-BASE*, which allows integers to be parsed and unparsed in bases other
than decimal.  I think this came from Maclisp, one of the more important
Lisp dialects that CL wanted to unify.  Maclisp defaulted to interpreting
digit-sequences as octal(!).

So in Common Lisp, when you want to make sure you're in "decimal" mode,
    (SETQ *READ-BASE* 10.)
makes more sense than just
    (SETQ *READ-BASE* 10)
and reads better than e.g.
    (SETQ *READ-BASE* (+ 1 1 1 1 1 1 1 1 1 1))

Sorry for the digression.  As for how Emacs should interpret numbers with a
trailing dot: If we want to keep Emacs Lisp aligned with Common Lisp, then
we should continue to treat them as decimal integers, and live with the
fact that users coming from other languages may have to learn to type "1.0"
instead of "1." when they want floats.  Personally I don't have a strong
opinion, although I have a slight preference to value CL compatibility
higher than convenience for non-native Lisp speakers in this case.  "1."
just doesn't look real float'y to me.
-- 
Simon.

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