On May 24, 2005, at 5:28 PM, John Meacham wrote:
[various ways of capturing options passed to functions discussed...]
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.
Ah, but imagine I don't have the module source handy. Which corresponds to True and which to False? Mostly, I stay away from enumerations whose order matters, making a particular exception for Bool and Ord. If the names are (as above) DontDoSomething | DoSomething, using a newtype plus a boolean conveys the same sense without the forgetfulness: newtype CreateParents = CreateParents Bool createDirectory (CreateParents False) -Jan-Willem Maessen