[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Chicken-hackers] [PATCH][5] types.db entries for the overflow-aware

From: lemonboy
Subject: Re: [Chicken-hackers] [PATCH][5] types.db entries for the overflow-aware ops
Date: Sun, 21 May 2017 17:14:02 +0200

Hi Peter,
I expect the `fxX?` procedures as 1:1 replacements of the standard
`fxN` ones with the
only exception being the way the overflow is handled.
The point where the two diverge is the handling of the input
parameters: while the latter
follow the garbage-in garbage-out philosophy the former takes a
"stricter" approach and
rejects the non-fixnum arguments by returning `#f`.
I think that's the by-product of a lax check on the input parameters
rather than a design
decision and even though this check works just fine in practice there
are some drawbacks:
- We can't give to their arguments the type `(or fixnum false)`, this
means we can't possibly
 warn the user if they pass the wrong argument (the standard
procedures allow this);
- There's no way to distinguish the result of `(fx+? 'foo 3)` from the
result of an
 overflowing calculation, couple it with the lack of any warning and
you're in for a nice bug


On 19 May 2017 at 22:54, Peter Bex <address@hidden> wrote:
> On Fri, May 19, 2017 at 10:48:38PM +0200, lemonboy wrote:
>> Hello hackers,
>> there's not much more to say.
> I'm wondering, is it defined only for fixnums and false, or is it
> part of the API that it allows any non-fixnum object?
> (fx+? 'hi 'there) => #f
> In that case, the type shouldn't be
> (fx+? (or fixnum false) (or fixnum false)) => (or fixnum false)
> but
> (fx+? * *) => (or fixnum false)
> Cheers,
> Peter

reply via email to

[Prev in Thread] Current Thread [Next in Thread]