On Tue, May 24, 2005 at 02:31:29PM -0400, robert dockins wrote:
One of the best bad example is the use of boolean as arguments.
Oh, yes. That's a pet peeve of mine. About 99% of boolean arguments should be meaningful two-valued enumerated types. It's literally a one-liner to create such an enumerated type, so there's no excuse.
The documentation effect and type safety provided by two-valued enumerated types is indeed much greater. But one needs a conversion from Bool to the enumeration if one wants to pass the result of a logic operation to the function. What about records with named fields, especially if more options are needed?
data CreateDirectoryOptions = Cons {createParents :: Bool}
createDirectory (Cons {createParents = True}) "dir"
I think it is easier just to declare it as Enum.. data ParentsFlag = DontCreateParents | CreateParents deriving(Enum) now (toEnum . fromEnum) will convert between ParentsFlag and Bool. John -- John Meacham - ⑆repetae.net⑆john⑈