9 Oct
2007
9 Oct
'07
3:35 p.m.
On 10/9/07, Johan Tibell
data Rope = Empty | Leaf | Node !Rope !Rope
The point is that Empty can only appear at the top by construction
How about indicating this in your data type? I.e., data Rope = Empty | NonEmptyRope data NonEmptyRope = Leaf | Node !NonEmptyRope !NonEmptyRope