Penultimate Element – Rich 4Clojure Problem 20 – See: https://github.com/PEZ/rich4clojure

rich4clojure_easy_problem_020.clj

(ns rich4clojure.easy.problem-020
  (:require [hyperfiddle.rcf :refer [tests]]))

;; = Penultimate Element =
;; By 4Clojure user: dbyrne
;; Difficulty: Easy
;; Tags: [seqs]
;; 
;; Write a function which returns the second to last
;; element from a sequence.

(def __ :tests-will-fail)

(comment
  
  )

(tests
  (__ (list 1 2 3 4 5)) := 4
  (__ ["a" "b" "c"]) := "b"
  (__ [[1 2] [3 4]]) := [1 2])

;; To participate, fork:
;; https://github.com/PEZ/rich4clojure

;; Post your solution below, please!

#(->> %
    reverse
    second)

(fn [sq]
(get (vec sq) (dec (dec (count (vec sq))))))

(defn second2last
[coll]
(first (drop 1 (reverse coll))))

(def __
  (fn [coll]
    (-> coll
        reverse
        second)))

(def __ (comp second reverse))

(def second-last (comp first (partial drop 1) reverse))

I forgot about second.

(fn [coll]
            (loop [x coll
                   last-two-el []]
              (if (= (count x) 1)
                (first last-two-el)
                (recur (rest x) (conj (drop 1 last-two-el)  (first x))))))

(def __ (comp second reverse))