Map Defaults – Rich 4Clojure Problem 156 – See: https://github.com/PEZ/rich4clojure

rich4clojure_elementary_problem_156.clj

(ns rich4clojure.elementary.problem-156
  (:require [hyperfiddle.rcf :refer [tests]]))

;; = Map Defaults =
;; By 4Clojure user: jaycfields
;; Difficulty: Elementary
;; Tags: [seqs]
;; 
;; When retrieving values from a map, you can specify
;; default values in case the key is not found:
;; 
;; 
;; (= 2 (:foo {:bar 0, :baz 1} 2))
;; 
;; 
;; However, what if you want the map itself to contain
;; the default values? Write a function which takes a
;; default value and a sequence of keys and constructs a
;; map.

(def __ :tests-will-fail)

(comment
  
  )

(tests
  (__ 0 [:a :b :c]) := {:a 0 :b 0 :c 0}
  (__ "x" [1 2 3]) := {1 "x" 2 "x" 3 "x"}
  (__ [:a :b] [:foo :bar]) := {:foo [:a :b] :bar [:a :b]})

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

;; Post your solution below, please!

(def __ (fn [v ks]
          (apply hash-map (interleave ks (repeat v)))))

(fn [value collection] (into {} (for [x collection] {x value})))

(def __ (fn [default coll]
          (reduce
           (fn [res val]
             (conj res {val default})) {} coll)))

(fn [def-value s] 
          (loop [x s
                 result {}]
            (if-not (seq x)  
              result
              (recur (rest x) (conj result {(first x) def-value})))))
              

  (def __ #(zipmap %2 (repeat %1)))

(defn __ [default key-collection]
    (reduce #(assoc %1 %2 default) {} key-collection))