On 8/10/07, Andrew Coppin
My program needs to make decisions based on a pair of boolean values. Encoding both values as a single algebraic data type means I have to keep "taking it apart" so I can work with it. I'm not sure how much time this wastes...
Incidentally, there is an argument that many (perhaps most) use of Bool should instead be custom datatypes. That is, instead of: type FooBar = (Bool, Bool) one should instead do something like data Foo = Foo | AntiFoo data Bar = Baz | Bo type FooBar = (Foo, Bar) which makes it clearer what's going on and harder to confuse the two booleans. Of course, now you have to replace \(foo, bar) -> if foo then ... else ... with \(foo, bar) -> if foo == Foo then ... else ... or \(foo, bar) -> case foo of { Foo -> ...; Bar -> ... } ---- Actually, that raises an interesting question. Is there a performance difference between "if foo == Foo ..." and "case Foo of ..."? I think JHC's case-hoisting should be able to transform the former into the latter, but does it?