Control.Lens.Internal.Deque

A Banker's deque based on Chris Okasaki's "Purely Functional Data Structures"

O(1). Calculate the size of a Deque

>>> size (fromList [1,4,6])3

O(n) amortized. Construct a Deque from a list of values.

>>> fromList [1,2]BD 1 [1] 1 [2]

O(1). Determine if a Deque is empty.

>>> Control.Lens.Internal.Deque.null emptyTrue

>>> Control.Lens.Internal.Deque.null (singleton 1)False

O(1). Generate a singleton Deque

>>> singleton 1BD 1 [1] 0 []