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

[David Kastrup]

Wolfgang Jenkner <address@hidden> writes:

> On Fri, Mar 14 2014, Stefan wrote:
>
>>> More important, it feels wrong coming from a Lisp background, as Common Lisp
>>> and Scheme both interpret "1." to be a floating point number.  I would
>>> support changing Emacs Lisp to be consistent with common practice, as there
>>> seems no point to being different and there are advantages to being
>>> consistent.  (Not during the feature freeze though, of course.)
>>
>> I'd tend to agree, indeed.
>
> 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;
>         
> And, to be really pedantic, let's add that `integer' and `float' are
> disjoint types, see [2],
>
>       The types rational and float are disjoint subtypes of type real.
>
> and [3],
>
>       The types integer and ratio are disjoint subtypes of type
>       rational.
>         
> This remark is actually pertinent here, because the emacs CL package
> seems to emulate these type relations (as far as corresponding objects
> exist in emacs-lisp).
>
> (cl-typep 1. 'integer)
> => t
> (cl-typep 1. 'float)
> => nil
>
> [1] http://www.lispworks.com/documentation/HyperSpec/Body/02_cbaa.htm
> [2] http://www.lispworks.com/documentation/HyperSpec/Body/t_real.htm
> [3] http://www.lispworks.com/documentation/HyperSpec/Body/t_ration.htm

And indeed:

$ clisp
  i i i i i i i       ooooo    o        ooooooo   ooooo   ooooo
  I I I I I I I      8     8   8           8     8     o  8    8
  I  \ `+' /  I      8         8           8     8        8    8
   \  `-+-'  /       8         8           8      ooooo   8oooo
    `-__|__-'        8         8           8           8  8
        |            8     o   8           8     o     8  8
  ------+------       ooooo    8oooooo  ooo8ooo   ooooo   8

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[1]> 1.
1
[2]> 1.0
1.0
[3]> 


-- 
David Kastrup