accumulate operation, which, given a collection and an
operation to perform on each element of the collection, returns a new
collection containing the result of applying that operation to each element of
the input collection.
Given the collection of numbers:
And the operation:
x => x * x)
Your code should be able to produce the collection of squares:
Check out the test suite to see the expected function signature.
Keep your hands off that collect/map/fmap/whatchamacallit functionality provided by your standard library! Solve this one yourself using other basic tools instead.
Conversation with James Edward Gray II https://twitter.com/jeg2
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
(ns accumulate-test (:require [clojure.test :refer [deftest is]] accumulate)) (defn- square [n] (* n n)) (defn- to-s [xs] (apply str xs)) (deftest empty-accumulation (is (=  (accumulate/accumulate square )))) (deftest accumulate-squares (is (= [1 4 9] (accumulate/accumulate square [1 2 3])))) (deftest accumulate-upcases (is (= ["HELLO", "WORLD"] (->> ["hello" "world"] (accumulate/accumulate clojure.string/upper-case) (map to-s))))) (deftest accumulate-reversed-strings (is (= ["eht" "kciuq" "nworb" "xof" "cte"] (->> ["the" "quick" "brown" "fox" "etc"] (accumulate/accumulate reverse) (map to-s))))) (deftest accumulate-recursively (is (= [["a1" "a2" "a3"] ["b1" "b2" "b3"] ["c1" "c2" "c3"]] (-> #(accumulate/accumulate (fn [n] (str % n)) [1 2 3]) (accumulate/accumulate "abc")))))
(ns accumulate) (defn accumulate [fun, coll] (loop [acc  coll coll] (if (empty? coll) acc (recur (conj acc (fun (first coll))) (rest coll)))))
A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.
Here are some questions to help you reflect on this solution and learn the most from it.