Thanks for the answer. (And doubly thanks for giving the answer I hoped for!)
I propose that ifThenElse and thenElseIf be added to the Prelude for Haskell'. While these names are a bit long, I think we want both functions and these names make the behaviors clear (to me, at least). Comments? -m Paul Hudak <[EMAIL PROTECTED]> writes: > Mike Gunter wrote: > >>I had hoped the "History of Haskell" paper would answer a question >>I've pondered for some time: why does Haskell have the if-then-else >>syntax? The paper doesn't address this. What's the story? >> >>thanks, >>-m >> >> > Thanks for asking about this -- it probably should be in the paper. > Dan Doel's answer is closest to the truth: > > I imagine the answer is that having the syntax for it looks nicer/is > clearer. "if a b c" could be more cryptic than "if a then b else c" > for some values of a, b and c. > > except that there was also the simple desire to conform to convention > here (I don't recall fewer parentheses being a reason for the choice). > In considering the alternative, I remember the function "cond" being > proposed instead of "if", in deference to Scheme and to avoid > confusion with people's expectations regarding "if". > > A related issue is why Haskell does not have a "single arm" > conditional -- i.e. an "if-then" form, which would evaluate to bottom > (i.e. error) if the predicate were false. This was actually > discussed, but rejected as a bad idea for a purely functional language. > > -Paul _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
