# Re: [racket-users] Re: Why is 3d3 a number?

```Patches to the reader for a more sane number syntax to be used in the
teaching languages are welcome. Note that we already have some of
these in place, as 1.2 reads as a rational in the teaching languages.```
```
Robby

On Tue, Sep 20, 2016 at 10:39 AM, Ben Greenman
<benjaminlgreen...@gmail.com> wrote:
> Whew, fantastic! Thank you.
> (Should I tell the Fundamentals I students about R6RS?)
>
>
> On Tue, Sep 20, 2016 at 11:32 AM, Asumu Takikawa <as...@simplyrobot.org>
> wrote:
>>
>> On 2016-09-20 11:27:07 -0400, Ben Greenman wrote:
>> >    Oh! Just found that common lisp used these for types:
>> >    - s = short
>> >    - f = single
>> >    - d = double
>> >    - l = long
>>
>> I think it's more specifically an R6RS thing. Quoth the standard:
>>
>>   In systems with inexact number objects of varying precisions, it may be
>> useful
>>   to specify the precision of a constant. For this purpose,
>> representations of
>>   number objects may be written with an exponent marker that indicates the
>>   desired precision of the inexact representation. The letters s, f, d,
>> and l
>>   specify the use of short, single, double, and long precision,
>> respectively.
>>   (When fewer than four internal inexact representations exist, the four
>> size
>>   specifications are mapped onto those available. For example, an
>> implementation
>>   with two internal representations may map short and single together and
>> long
>>   and double together.) In addition, the exponent marker e specifies the
>> default
>>   precision for the implementation. The default precision has at least as
>> much
>>   precision as double, but implementations may wish to allow this default
>> to be
>>   set by the user.
>>
>>   http://www.r6rs.org/final/html/r6rs/r6rs-Z-H-7.html#node_sec_4.2.8
>>
>> Cheers,
>> Asumu
>
>
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