Re: Shrinking the C core

[Ihor Radchenko]

Eli Zaretskii <eliz@gnu.org> writes:

>> (let ((a 10))
>>   (setq a (+ a 100))
>>   (floor a nil))
>> 
>> During compilation of the above code, the compiler will know that a is a
>> positive integer.
>
> It will?  What happens if a overflows?

It will not, right? Because we do know all the values at compile time in
the above example. I am not sure if we can as far as checking the value
range at compile time, but it is at least theoretically possible.

>> Therefore, CHECK_NUMBER, NILP, and FLOATP are not
>> necessary and can be omitted in the call to `floor':
>
> If you want to program in C or Fortran, then program in C or Fortran.
> Lisp is an interpreted environment that traditionally includes safety
> nets.  People actually complain to us, and rightfully so, when Emacs
> crashes or produces corrupted results instead if signaling an error
> pointing out invalid input or other run-time problems.

I did not mean to disable checks. I just meant that when the types and
possibly value ranges are known at compile time, these checks can be
safely omitted. Without compromising safety.

-- 
Ihor Radchenko // yantar92,
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