Functional Batched Deque

A functional deque based on Okasaki’s work and Jens Axel Søgaard’s code.

(require (planet jaymccarthy/batched-deque))

(deque? v) → boolean?

v : any/c

Tests deque-ness.

non-empty-deque/c : contract?

A contract for non-empy deques.

deque-empty : deque?

An empty deque.

(deque-empty? dq) → boolean?

dq : deque?

Returns true if dq is empty.

(deque-unshift v dq) → non-empty-deque/c

v : any/c

dq : deque?

Returns a deque that is the same as dq except that it starts with v.

(deque-push v dq) → non-empty-deque/c

v : any/c

dq : deque?

Returns a deque that is the same as dq except that it end with v.

(deque-shift dq) → deque?

dq : non-empty-deque/c

Returns a deque that is the same as dq except it is missing the first element.

(deque-pop dq) → deque?

dq : non-empty-deque/c

Returns a deque that is the same as dq except it is missing the last element.

(deque-last dq) → any/c

dq : non-empty-deque/c

Returns the last element of dq.

(deque-first dq) → any/c

dq : non-empty-deque/c

Returns the first element of dq.

(deque-elements dq) → (listof any/c)

dq : deque?

Returns elements of dq as a list.

(deque-map f dq) → deque?

f : (-> any/c any/c)

dq : deque?

Maps f over dq, returning a new deque.

(deque-length dq) → exact-nonnegative-integer?

dq : deque?

Returns the number of elements in dq.