OT (partially): about promotion of integers

[deadalnix]

On Tuesday, 11 December 2012 at 21:57:38 UTC, Walter Bright wrote:
> On 12/11/2012 10:45 AM, bearophile wrote:
>> Walter Bright:
>>
>>> Why stop at 64 bits? Why not make there only be one integral 
>>> type, and it
>>> is of whatever precision is necessary to hold the value? This 
>>> is quite
>>> doable, and has been done.
>>
>> I think no one has asked for *bignums on default* in this 
>> thread.
>
> I know they didn't ask. But they did ask for 64 bits, and the 
> exact same
> argument will apply to bignums, as I pointed out.
>

Agreed.

>>> But at a terrible performance cost.
>> Nope, this is a significant fallacy of yours. Common lisp (and 
>> OCaML) uses
>> tagged integers on default, and they are very far from being 
>> "terrible".
>> Tagged integers cause no heap allocations if they aren't 
>> large. Also the
>> Common Lisp compiler in various situations is able to infer an 
>> integer can't
>> be too much large, replacing it with some fixnum. And it's 
>> easy to add
>> annotations in critical spots to ask the Common Lisp compiler 
>> to use a
>> fixnum, to squeeze out all the performance.
>
> I don't notice anyone reaching for Lisp or Ocaml for high 
> performance applications.
>

I don't know about common LISP performances, never tried it in 
something where that really matter. But OCaml is really very 
performant. I don't know how it handle integer internally.

> That's irrelevant to this discussion. It is not a problem with 
> the language.
> Anyone can improve the library one if they desire, or do their 
> own.
>

The library is part of the language. What is a language with no 
vocabulary ?

>> I think the compiler doesn't perform on BigInts the 
>> optimizations it does on
>> ints, because it doesn't know about bigint properties.
>
> I think the general lack of interest in bigints indicate that 
> the builtin types work well enough for most work.

That argument is fallacious. Something more used don't really 
mean better. OR PHP and C++ are some of the best languages ever 
made.