7 Mar
2007
7 Mar
'07
6:43 p.m.
Joachim,
Don't stop at the booleans. Next you can define the natural numbers by
newtype Number = N (forall a.(a->a) -> (a->a))
--
Dan
On 3/7/07, Joachim Breitner
For a while I have been thinking: Isn't there a way to get rid of the intermediate Maybe construct in a common expression like "fromMaybe default . lookup". It seems that a way to do that would be to pass more information to the Maybe-generating function: What to do with a Just-Value, and what to return in case of Nothing. This leads to a new definion of the Maybe data type as a function. Later I discovered that this seems to work for any algebraic data type.