Converting from 0 and 1 to -1 and 1
in [General Programming]
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From: Jussi Piitulainen on 8 May 2010 02:39 Pascal J. Bourguignon writes: .... > Now, the real why is why would anybody try to program anything in > BrainFuck^W a language that doesn't have "ternary operators"? .... A related weakness in popular programming languages is that they have only one. More should be added. Then people would learn to call the conditional operator "the conditional operator". Anything vaguely usable with three operands would do. Median of three numbers. Majority vote of three booleans. I think Church also had something he called conditional disjunction, which I even looked up but then forgot, so I'm not sure now if its ternary. Maybe we could have a form of Kronecker delta that evaluates to the third argument if the first and second are equal, and otherwise evaluates to zero. Say x!y:z == ((x == y) ? z : 0). Then yet another solution to the present problem would be this: x!0:-1 + x!1:1
From: Ben Bacarisse on 8 May 2010 08:17 Jussi Piitulainen <jpiitula(a)ling.helsinki.fi> writes: > Pascal J. Bourguignon writes: > ... >> Now, the real why is why would anybody try to program anything in >> BrainFuck^W a language that doesn't have "ternary operators"? > ... > > A related weakness in popular programming languages is that they have > only one. More should be added. Then people would learn to call the > conditional operator "the conditional operator". In a similar vein, there is no reason why a conditional operator should be limited to being ternary, as Pascal's language of choice (along with several others) makes clear. > Anything vaguely usable with three operands would do. Median of three > numbers. Majority vote of three booleans. I think Church also had > something he called conditional disjunction, which I even looked up > but then forgot, so I'm not sure now if its ternary. It is ternary, but it is essentially the same as ?: when limited to truth-values and written in what is now thought of as an odd order: [p,q,r] means q?p:r when p, q and r are all true/false. (Thanks for prompting me to look this up.) -- Ben.
From: pete on 8 May 2010 09:07 Ben Bacarisse wrote: > > Jussi Piitulainen <jpiitula(a)ling.helsinki.fi> writes: > > > Pascal J. Bourguignon writes: > > ... > >> Now, the real why is why would anybody try to program anything in > >> BrainFuck^W a language that doesn't have "ternary operators"? > > ... > > > > A related weakness in popular programming > > languages is that they have > > only one. More should be added. Then people would learn to call the > > conditional operator "the conditional operator". > > In a similar vein, there is no reason why > a conditional operator should > be limited to being ternary, > as Pascal's language of choice (along with > several others) makes clear. > > > Anything vaguely usable with three operands would do. > > Median of three > > numbers. Majority vote of three booleans. I think Church also had > > something he called conditional disjunction, which I even looked up > > but then forgot, so I'm not sure now if its ternary. > > It is ternary, but it is essentially the same as ?: when limited to > truth-values and written in what is now thought of as an odd order: > [p,q,r] means q?p:r when p, q and r are all true/false. (Thanks for > prompting me to look this up.) I think the point that Jussi Piitulainen is making, is that operators should be named by what they do; "the ternary operator" is a bad name. If C were to be changed so that the only binary operator were the assignment operator, then it should still be called "the assignment operator" and not be called "the binary operator". -- pete
From: bart.c on 8 May 2010 09:28 "Jussi Piitulainen" <jpiitula(a)ling.helsinki.fi> wrote in message news:qotzl0ahp7j.fsf(a)ruuvi.it.helsinki.fi... > Pascal J. Bourguignon writes: > ... >> Now, the real why is why would anybody try to program anything in >> BrainFuck^W a language that doesn't have "ternary operators"? > ... > > A related weakness in popular programming languages is that they have > only one. More should be added. Then people would learn to call the > conditional operator "the conditional operator". Maybe there should be none. The C-style a?b:c operator has a rather odd syntax, but it just does the same thing as: if a then b else c fi (where a language allows this as an expression), or (a|b|c). > Anything vaguely usable with three operands would do. Median of three > numbers. Majority vote of three booleans. Many of these are just special cases of N-operand operators. The challenge is an operator syntax that allows an arbitrary number of operands (and which doesn't look like a single operand which happens to be a list, although that is another way of doing it). Sometimes, multiple ordinary operators can be combined in a special way: a<=b=c<d returns true or false (but I'm not sure what category you'd put that in: is a<b<c a ternary operation?). -- Bartc
From: Ben Bacarisse on 8 May 2010 09:52
pete <pfiland(a)mindspring.com> writes: > Ben Bacarisse wrote: >> >> Jussi Piitulainen <jpiitula(a)ling.helsinki.fi> writes: >> >> > Pascal J. Bourguignon writes: >> > ... >> >> Now, the real why is why would anybody try to program anything in >> >> BrainFuck^W a language that doesn't have "ternary operators"? >> > ... >> > >> > A related weakness in popular programming >> > languages is that they have >> > only one. More should be added. Then people would learn to call the >> > conditional operator "the conditional operator". >> >> In a similar vein, there is no reason why >> a conditional operator should >> be limited to being ternary, >> as Pascal's language of choice (along with >> several others) makes clear. <snip> > I think the point that Jussi Piitulainen is making, > is that operators should be named by what they do; > "the ternary operator" is a bad name. Yes, I got that. I was extending the complaint by saying that the conditional operator need not be ternary. There are two reasons why it's the wrong name. I was giving the other one. [To be fail (since this has gone way over budget for such a small matter) I don't think Pascal was using the term "ternary operator" as a name for the conditional operator. His remark seems to say no more than that a language without ternary operators probably has no conditional operator.] <snip> -- Ben. |