ICounted

protocol

since v0.0-927

implemented for ArrayChunk BlackNode ChunkBuffer ChunkedSeq EmptyList HashMapLite IndexedSeq IntegerRange IntegerRangeChunk List MapEntry ObjMap PersistentArrayMap PersistentArrayMapSeq PersistentHashMap PersistentHashSet PersistentQueue PersistentTreeMap PersistentTreeMapSeq PersistentTreeSet PersistentVector RSeq RedNode SetLite Subvec TransientArrayMap TransientHashMap TransientHashSet TransientVector VectorLite nil

Source docstring:

Protocol for adding the ability to count a collection in constant time.

Source code @ clojurescript:src/main/cljs/cljs/core.cljs

(defprotocol ICounted
  (^number -count [coll]
    "Calculates the count of coll in constant time. Used by cljs.core/count."))