clojure.core.reducers — org.clojure/clojure 1.9.0

A library for reduction and parallel folding. Alpha and subject to change. Note that fold and its derivatives require Java 7+ or Java 6 + jsr166y.jar for fork/join support. See Clojure's pom.xml for the dependency info.

append! clj

(append! acc x)

.adds x to acc and returns acc

cat clj

(cat)

(cat ctor)

(cat left right)

A high-performance combining fn that yields the catenation of the reduced values. The result is reducible, foldable, seqable and counted, providing the identity collections are reducible, seqable and counted. The single argument version will build a combining fn with the supplied identity constructor. Tests for identity with (zero? (count x)). See also foldcat.

CollFold clj protocol

coll-fold clj

(coll-fold coll n combinef reducef)

drop clj

(drop n)

(drop n coll)

Elides the first n values from the reduction of coll.

filter clj

(filter pred)

(filter pred coll)

Retains values in the reduction of coll for which (pred val) returns logical true. Foldable.

fjtask clj

(fjtask f)

flatten clj

(flatten)

(flatten coll)

Takes any nested combination of sequential things (lists, vectors, etc.) and returns their contents as a single, flat foldable collection.

fold clj

(fold reducef coll)

(fold combinef reducef coll)

(fold n combinef reducef coll)

Reduces a collection using a (potentially parallel) reduce-combine strategy. The collection is partitioned into groups of approximately n (default 512), each of which is reduced with reducef (with a seed value obtained by calling (combinef) with no arguments). The results of these reductions are then reduced with combinef (default reducef). combinef must be associative, and, when called with no arguments, (combinef) must produce its identity element. These operations may be performed in parallel, but the results will preserve order.

foldcat clj

(foldcat coll)

Equivalent to (fold cat append! coll)

folder clj

(folder coll xf)

Given a foldable collection, and a transformation function xf, returns a foldable collection, where any supplied reducing fn will be transformed by xf. xf is a function of reducing fn to reducing fn.

map clj

(map f)

(map f coll)

Applies f to every value in the reduction of coll. Foldable.

mapcat clj

(mapcat f)

(mapcat f coll)

Applies f to every value in the reduction of coll, concatenating the result colls of (f val). Foldable.

monoid clj

(monoid op ctor)

Builds a combining fn out of the supplied operator and identity constructor. op must be associative and ctor called with no args must return an identity value for it.

pool clj

reduce clj

(reduce f coll)

(reduce f init coll)

Like core/reduce except: When init is not provided, (f) is used. Maps are reduced with reduce-kv

reducer clj

(reducer coll xf)

Given a reducible collection, and a transformation function xf, returns a reducible collection, where any supplied reducing fn will be transformed by xf. xf is a function of reducing fn to reducing fn.

remove clj

(remove pred)

(remove pred coll)

Removes values in the reduction of coll for which (pred val) returns logical true. Foldable.

take clj

(take n)

(take n coll)

Ends the reduction of coll after consuming n values.

take-while clj

(take-while pred)

(take-while pred coll)

Ends the reduction of coll when (pred val) returns logical false.