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Re: kawa numerics unstable


thanks for the clarification. it's not a problem, was just 
taken by surprise in places where i had assumed equalness 
(i apparently need to watch the changelogs more closely). 
the advantages you describe are worth the minor code 
adaptations.


Per Bothner writes:
 > On 11/12/2009 11:56 AM, thomas kirk wrote:
 > >
 > > not clear that this is a bug, but it's a change in behavior. before
 > > your numerics changes, kawa would automatically convert java numeric
 > > types to kawa numerics (in some situations, at least):
 > >
 > >      #|kawa:34|# (invoke (invoke-static<java.lang.Integer>  'parseInt "1") 'getClass)
 > >      class gnu.math.IntNum
 > >      #|kawa:35|# (scheme-implementation-version)
 > >      1.9.3 (revision 6275M)
 > >
 > >
 > > in the latest revision, this conversion doesn't happen:
 > >      #|kawa:70|# (invoke (invoke-static<java.lang.Integer>  'parseInt "1") 'getClass)
 > >      class java.lang.Integer
 > >      #|kawa:71|# (scheme-implementation-version)
 > >      1.9.90 (revision 6451M)
 > >
 > >
 > > so, is the intention that code should now do this conversion explicitly?
 > > or is it an unintended consequence?
 > 
 > This is intentional.  There are advantages and disadvantages, of course.
 > One advantage of the change is that we're more "Java-compatible",
 > in that 'int' and 'java.lang.Integer' are more equivalent.  This
 > matches both Java5 auto-boxing, and java.lang.reflect, so it seems
 > desirable.
 > 
 > (Slightly related: Kawa now uses Java5 varargs to implement
 > its own varargs, and calling a Java varargs function "works".)
 > 
 > To reduce some of the "surprise" Kawa now can handle arithmetic
 > on java.lang.Integer - but that uses 32-bit arithmetic, rather than
 > unlimited-precision IntNum arithmetic.
 > 
 > Does this change cause problems?  If so: is there something Kawa
 > can do to ameliorate the problem?
 > -- 
 > 	--Per Bothner
 > per@bothner.com   http://per.bothner.com/


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