.gitignore

node_modules/
package-lock.json

package.json

{
  "name": "palindrome",
  "version": "1.0.0",
  "description": "",
  "homepage": "https://gist.github.com/b19a2f0134bbda9b79e1414889d4dec0",
  "bugs": {
    "url": "https://gist.github.com/b19a2f0134bbda9b79e1414889d4dec0"
  },
  "repository": {
    "type": "git",
    "url": "git+ssh://git@gist.github.com/b19a2f0134bbda9b79e1414889d4dec0.git"
  },
  "license": "ISC",
  "author": "vvgomes",
  "type": "module",
  "main": "palindrome.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "dependencies": {
    "ramda": "^0.32.0"
  }
}

palindrome.clj

(ns palindrome
  (:require [clojure.test :refer [deftest is]]))

(def drop-edges
  (comp drop-last rest))

(defn equal-edges? [w]
  (= (first w) (last w)))

(def too-small?
  (comp (partial > 2) count))

(defn palindrome? [w]
  (or
   (too-small? w)
   (and
    (equal-edges? w)
    (palindrome? (drop-edges w)))))

(deftest test-palindrome?->yes!
  (is (palindrome? ""))
  (is (palindrome? "a"))
  (is (palindrome? "aa"))
  (is (palindrome? "aba"))
  (is (palindrome? "abba"))
  (is (palindrome? "abcdedcba")))

(deftest test-palindrome?->no!
  (is (not (palindrome? "ab")))
  (is (not (palindrome? "abb")))
  (is (not (palindrome? "abaa")))
  (is (not (palindrome? "abcdeecba"))))

palindrome.js

import {
  head, last, equals, and, equals,
  and, tail, gt, all, compose
} from "ramda";

const dropEdges =
  compose(dropLast(1), tail);

const equalEdges = (word) =>
  equals(head(word), last(word));

const tooSmall =
  comp(gt(2), length);

const isPalindrome = (word) =>
  tooSmall(word) || and(equalEdges(word), isPalindrome(dropEdges(word)));

all(equals(true), [
  isPalindrome(""),
  isPalindrome("a"),
  isPalindrome("aa"),
  isPalindrome("aba"),
  isPalindrome("abba"),
  isPalindrome("abcdedcba")
]);

all(equals(false), [
  isPalindrome("ab"),
  isPalindrome("abb"),
  isPalindrome("abaa"),
  isPalindrome("abcdeecba")
]);