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
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