Do you have any reason not to do the above?
Yes, the subset types that I wish to define are not clean partitions,
though my example does suggest this. Let's say that the definition of
Foo is now
data Foo = One | Two | Three | Four | Five | Six
while Odd and Even remain the same. I would further like to define
Triangular, which I will do incorrectly for consistency.
data Triangular = One | Three | Six
I could not accommodate this definition using your scheme, correct?
Thanks,
Brian
On Sun, Jul 26, 2009 at 9:14 PM, Felipe Lessa
On Sun, Jul 26, 2009 at 09:01:22PM -0700, Brian Troutwine wrote:
Hello all.
I would like to define a data type that is the super-set of several types and then each of the proper subset types. For example:
data Foo = O !Odd | E !Even
data Odd = One | Three data Even = Two | Four
This, of course, does not work. It seems that such a thing should possible to express entirely in the type system, but I cannot think of how. Would someone be so kind as to explain how this sort of thing can be accomplished?
Do you have any reason not to do the above?
-- Felipe. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe