Numbers in Kawa

[Per Bothner]

On 04/27/2012 02:05 PM, Jamison Hope wrote:
> That does seem erroneous. I feel like (string-ref "abc" 1.0) should work,
> though [with a warning], so perhaps it should be an error iff the float
> isn't already integer-valued?

RnRS does require the index to be an exact non-negative integer,
so does not allow this.

> Worse, the numeric conversions aren't consistent. IMHO if you can convert
> to an int, you should be able to convert to an integer, too.

I agree.

> #|kawa:1|# (as int 10.0)
> /dev/stdin:1:9: warning - saw float where int expected
> 10
> #|kawa:2|# (integer? 10.0)
> #t
> #|kawa:3|# (as integer 10.0)
> /dev/stdin:3:13: warning - type DFloNum is incompatible with required
> type integer
> /dev/stdin:3:1: warning - cannot convert literal (of type
> gnu.math.DFloNum) to Type integer

I agree this is a bug.  Part of the problem is that Kawa doesn't
distinguish between implicit and explicit type conversions.  This
should be fixed, though working out the exact rules is a bit tricky.
(I wrote a proposal for what to do in an old email, but I don't
remember the specifics.)

I.e. I think converting float/double to int or integer is ok
when the conversion is explicit, but not when the conversion is
implicit (as in wrong argument type).
-- 
	--Per Bothner
per@bothner.com   http://per.bothner.com/