22 Apr
2003
22 Apr
'03
4:08 p.m.
Hello Peter,
I don't know why you mind the bar. It always denotes disjoint union.
signum x | x < 0 = -1 | x == 0 = 0 | otherwise = 1 The guards are not disjoint and '|' is not an operator, it *begins* a guarded expression.
data Tree a = Bin (Tree a) a (Tree a) | Nil
directly represents the domain equation whose least solution is the semantics of Tree a. It cannot be written more clearly.
:-) We're talking first-year students here. Greetings, Arjan