Ranges and the Enum class
wnoise at ofb.net
Mon Mar 20 20:47:41 EST 2006
On 2006-03-20, Wolfgang Jeltsch <wolfgang at jeltsch.net> wrote:
> Am Freitag, 17. März 2006 18:49 schrieb Ross Paterson:
>> Also, toEnum and fromEnum would make more sense mapping from and to
> Why do we need toEnum and fromEnum at all? As far as I know, they are merely
> there to help people implement things like enumFrom.
Which could still be useful.
> It's often not clear
> how toEnum and fromEnum should look like. How should they be implemented for
> Time.Day, for example? Should the days corresponds to the integers 0 to 6 or
> 1 to 7?
I believe that 0 to n-1 is the standard representation that deriving Enum currently
>> It seems that succ and pred are unused.
> No, I use them. In my opinion, it makes much more sense to write succ n than
> n + 1.
Agreed, for non-arithmetical types.
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