| Symbol | Type and constructors |
|---|---|
data FingerTree a = Empty
| Single a
| Deep (Digit a) (FingerTree (Node a)) (Digit a)
| |
| (none) |
data Digit a = One a | Two a a | Three a a a | Four a a a a |
data Node a = Node2 a a | Node3 a a a | |
| elements of arbitrary type |