• Russ Lewis (27/27) May 09 2002 OddesE asked the question:
• OddesE (12/39) May 09 2002 At the moment the contract checks (in and out conditions)
• Stephen Fuld (9/31) May 09 2002 Well, if you thought there was a possibility of the argument to a square
• Russell Borogove (4/11) May 10 2002 I gots two words for ya:

Russ Lewis <spamhole-2001-07-16 deming-os.org> writes:

OddesE asked the question:
    What is the square root of -4?

It got me thinking...it would be cool to have 2 versions of sqrt, one
that returns floats, and the other that reports complex numbers.  You of
course could differentiate between them by giving two names, but what if
you could just specify different in conditions?

    double sqrt(double val)
    in {
        assert(val >= 0);
    }
    body { ... };
    complex sqrt(complex val)
    in {
        assert(val < 0);
    }
    body { ... };

You can see that the in conditions don't overlap, so it's totally clear
which version needs to be used, given any input value.  Most times,
compiler will be able to choose the proper version at compile time.  In
cases where it can't, then it can put in a runtime check, along with
implicit casts from double to float as necessary.

Thoughts?

--
The Villagers are Online! villagersonline.com

.[ (the fox.(quick,brown)) jumped.over(the dog.lazy) ]
.[ (a version.of(English).(precise.more)) is(possible) ]
?[ you want.to(help(develop(it))) ]

"OddesE" <OddesE_XYZ hotmail.com> writes:

"Russ Lewis" <spamhole-2001-07-16 deming-os.org> wrote in message
news:3CDAE6AD.712A3C1D deming-os.org...
 OddesE asked the question:
     What is the square root of -4?

 It got me thinking...it would be cool to have 2 versions of sqrt, one
 that returns floats, and the other that reports complex numbers.  You of
 course could differentiate between them by giving two names, but what if
 you could just specify different in conditions?

     double sqrt(double val)
     in {
         assert(val >= 0);
     }
     body { ... };
     complex sqrt(complex val)
     in {
         assert(val < 0);
     }
     body { ... };

 You can see that the in conditions don't overlap, so it's totally clear
 which version needs to be used, given any input value.  Most times,
 compiler will be able to choose the proper version at compile time.  In
 cases where it can't, then it can put in a runtime check, along with
 implicit casts from double to float as necessary.

 Thoughts?

 --
 The Villagers are Online! villagersonline.com

 .[ (the fox.(quick,brown)) jumped.over(the dog.lazy) ]
 .[ (a version.of(English).(precise.more)) is(possible) ]
 ?[ you want.to(help(develop(it))) ]

At the moment the contract checks (in and out conditions)
are removed from release builds. And what if the conditions
do overlap? Mmm I'm not sure about this one....
Better give them different names I think.

--
Stijn
OddesE_XYZ hotmail.com
http://OddesE.cjb.net
_________________________________________________
Remove _XYZ from my address when replying by mail

"Stephen Fuld" <s.fuld.pleaseremove att.net> writes:

"Russ Lewis" <spamhole-2001-07-16 deming-os.org> wrote in message
news:3CDAE6AD.712A3C1D deming-os.org...
 OddesE asked the question:
     What is the square root of -4?

 It got me thinking...it would be cool to have 2 versions of sqrt, one
 that returns floats, and the other that reports complex numbers.  You of
 course could differentiate between them by giving two names, but what if
 you could just specify different in conditions?

     double sqrt(double val)
     in {
         assert(val >= 0);
     }
     body { ... };
     complex sqrt(complex val)
     in {
         assert(val < 0);
     }
     body { ... };

 You can see that the in conditions don't overlap, so it's totally clear
 which version needs to be used, given any input value.  Most times,
 compiler will be able to choose the proper version at compile time.  In
 cases where it can't, then it can put in a runtime check, along with
 implicit casts from double to float as necessary.

 Thoughts?

Well, if you thought there was a possibility of the argument to a square
root function being negative, you could cast the integer or real into a
complex.  This seems sort of like casting an integer into a real before
division if you want the fractional part.

--
 - Stephen Fuld
   e-mail address disguised to prevent spam

Russell Borogove <kaleja estarcion.com> writes:

Russ Lewis wrote:
 OddesE asked the question:
     What is the square root of -4?
 
 It got me thinking...it would be cool to have 2 versions of sqrt, one
 that returns floats, and the other that reports complex numbers.  You of
 course could differentiate between them by giving two names, but what if
 you could just specify different in conditions?

I gots two words for ya:

"unsigned float"

/me runs and hides