An implementation of the confluently persistent vector data structure introduced in Bagwell, Rompf, "RRB-Trees: Efficient Immutable Vectors", EPFL-REPORT-169879, September, 2011.

RRB-Trees build upon Clojure's PersistentVectors, adding logarithmic time concatenation and slicing.

The main API entry points are flexvec.core/catvec, performing vector concatenation, and flexvec.core/subvec, which produces a new vector containing the appropriate subrange of the input vector (in contrast to clojure.core/subvec, which returns a view on the input vector).

flexvec's vectors can store objects or unboxed primitives. The implementation allows for seamless interoperability with clojure.lang.PersistentVector, clojure.core.Vec (more commonly known as gvec) and clojure.lang.APersistentVector$SubVector instances: flexvec.core/catvec and flexvec.core/subvec convert their inputs to flexvec.rrbt.Vector instances whenever necessary (this is a very fast constant time operation for PersistentVector and gvec; for SubVector it is O(log n), where n is the size of the underlying vector).

flexvec.core also exports its own versions of vector, vector-of and vec which always produce flexvec.rrbt.Vector instances. Note that vector-of accepts :object as one of the possible type arguments, in addition to keywords naming primitive types.


(require '[flexvec.core :as fv])

;; read the overview at the REPL
(doc flexvec.core)

;; functions meant for public consumption
(doc fv/subvec)
(doc fv/catvec)
(doc fv/vector)
(doc fv/vector-of)
(doc fv/vec)

;; apply catvec and subvec to regular Clojure vectors
(fv/catvec (vec (range 1234)) (vec (range 8765)))
(fv/subvec (vec (range 1024)) 123 456)

;; for peeking under the hood
(require '[flexvec.debug :as dv])
(dv/dbg-vec (fv/catvec (vec (range 1234)) (vec (range 8765))))

Future development

Please note that patches will only be accepted from developers who have submitted the Clojure CA and would be happy with the code they submit to flexvec becoming part of the Clojure project.

Current TODO list:

  1. tests;

  2. benchmarks;

  3. performance: general perf tuning, efficient catvec implementation (to replace current seq-ops-based impl);

  4. transients;

  5. ClojureScript version.

Clojure(Script) code reuse

flexvec's vectors support the same basic functionality regular Clojure's vectors do (with the omissions listed above). Where possible, this is achieved by reusing code from Clojure's gvec and ClojureScript's PersistentVector implementations. The Clojure(Script) source files containing the relevant code carry the following copyright notice:

Copyright (c) Rich Hickey. All rights reserved.
The use and distribution terms for this software are covered by the
Eclipse Public License 1.0 (
which can be found in the file epl-v10.html at the root of this distribution.
By using this software in any fashion, you are agreeing to be bound by
  the terms of this license.
You must not remove this notice, or any other, from this software.


Copyright © 2012 Michał Marczyk

Distributed under the Eclipse Public License, the same as Clojure.