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*To*: Vassil Nikolov <vnikolov@x>*Subject*: Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0*From*: John Cowan <cowan@x>*Date*: Thu, 20 Dec 2012 16:49:46 -0500*Cc*: scheme-reports <scheme-reports@x>*In-reply-to*: <m2623xjr8i.fsf@pobox.com>*References*: <20121215204015.GG13463@mercury.ccil.org> <87obhv3ts0.fsf@tines.lan> <20121215231548.GC10312@mercury.ccil.org> <87bodu4r0r.fsf@tines.lan> <20121216041031.GE10312@mercury.ccil.org> <87pq25yh5s.fsf@tines.lan> <20121219221955.GH4477@mercury.ccil.org> <CAMMPzYP_=CbUkLJOHQbrqYQCRtrvU8PC36D-OQyMe0DyVZbp0g@mail.gmail.com> <87zk19wmzv.fsf@tines.lan> <m2623xjr8i.fsf@pobox.com>

Vassil Nikolov scripsit: > Well, I believe that another point of view is preferable, namely, > that (imag-part z) => 0 means that z is (certainly) a real number > and that (imag-part z) => 0.0 means that z is a complex number very > near and possibly, but not necessarily, on the real axis [*]. > (Therefore, (imag-part 2.0) => 0.) But that's just my 2/100+0i. I agree, and so did the R6RS team, and so did the R7RS WG at one time. But we ended up deciding that it was too subtle a change from the established R5RS semantics that a number is real iff its imaginary part is zero, exact or inexact. People's programs might stop working without their understanding quite why. R6S provides a workaround in the form of `real-valued?`, `rational-valued?`, and `integer-valued?` procedures, which provide the R5RS semantics (though without saying so). But our WG felt that nobody would be able to remember the difference between `real?` and `real-valued?` in actual use. The Pure language, which doesn't have historical baggage, uses the R6RS interpretation. -- May the hair on your toes never fall out! John Cowan --Thorin Oakenshield (to Bilbo) cowan@x _______________________________________________ Scheme-reports mailing list Scheme-reports@x http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports

**References**:**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*John Cowan <cowan@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Mark H Weaver <mhw@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*John Cowan <cowan@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Mark H Weaver <mhw@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*John Cowan <cowan@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Mark H Weaver <mhw@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*John Cowan <cowan@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Alex Shinn <alexshinn@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Mark H Weaver <mhw@x>

**Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0***From:*Vassil Nikolov <vnikolov@x>

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