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cat (clj)
(source)function
(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.
Examples
clojure
(ns clojure.test-clojure.reducers
(:require [clojure.core.reducers :as r]
[clojure.test.generative :refer (defspec)]
[clojure.data.generators :as gen])
(:use clojure.test))
(defequivtest test-mapcat
[mapcat r/mapcat #(into [] %)]
[(fn [x] [x])
(fn [x] [x (inc x)])
(fn [x] [x (inc x) x])])
(deftest test-mapcat-obeys-reduced
(is (= [1 "0" 2 "1" 3]
(->> (concat (range 100) (lazy-seq (throw (Exception. "Too eager"))))
(r/mapcat (juxt inc str))
(r/take 5)
(into [])))))