I'm reading Chris Okasaki's "Purely Functional Data Structures", and some
of his Haskell is confusing me. He defines the type Color and RedBlackSet
as:
data Color = R | B
data RedBlackSet a = E | T Color (RedBlackSet a) a (RedBlackSet a)
and then later he defines a function insertSet:
insertSet x s = T B a y b
where ins E = T R E x E
...
T _ a y b = ins s
What I don't understand is his use of the "T" constructor, both at
insertSet x s = T B a y b
and in the where statement:
T _ a y b = ins s
Is "T" being redefined, so the "T" called in the first line is a new
function that happens to be called "T" which is defined in the where
statement? If that was the case, I would expect this to work:
insertSet x s = foo B a y b
where ins E = foo R E x E
...
foo _ a y b = ins s
but it does not. If anyone can explain what's going on here, I'd appreciate
it. Thank you!
Justin
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
