Re: Extending Lua for multiple light userdata types

[Hans Hagen <pragma@...>]

On 11/14/2012 12:40 AM, Roberto Ierusalimschy wrote:
> > This conversation started in IRC and I fully agree with Rena which
> > will come as no surprise as I have said this before. It is 2012 and
> > yet Lua has no access to a 64 bit int(in fact from the C API point of
> > view it was even considered to remove the default lua_Integer as a
> > typedef for ptrdiff_t ), before too long the majority of people will
> > not care about 32 bit systems and even arm is getting a 64 bit
> > version, when will Rio Lua have a 64 bit int? When will we be able to
> > sanely do bit operations on 64bit types without resorting using
> > strings *?
>
> I have been playing a little with the idea of introducing an integer
> type in Lua. I have intended to present some initial thoughts in the
> workshop.
>
> The overall idea is quite simple. There will be two kinds of numbers,
> integers and floats. All operations except division result in an
> integer if both operands are integers and in float otherwise. There
> will be two divisions: float division (the usual '/') always have
> a float result, integer division ('//'??) always have an integer
> result.

maybe ":" as single token, in NL kids at schools start with (positive) 
integers and the : is used as division symbol learn division (but 
anyway, // looks visually ok too)

> Except for overflows, all operations have the same results
> independently of whether operands are represented as floats or
> as integers; but there is no automatic conversion on overflows:
> operations with integers should overflow like unsigned integers
> in C.

Does 1.0 represent an integer or float? or is it:

1.0 * 123 => float
1   * 123 => integer

> (So, the fact that a number is represented as an integer or as
> a float is explicit and visible to the programmer, but for most
> mundane tasks this distinction is irrelevant.)

indeed

just curious: what is the expected impact on memory and speed?

Hans

-----------------------------------------------------------------
                                          Hans Hagen | PRAGMA ADE
              Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
    tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                             | www.pragma-pod.nl
-----------------------------------------------------------------