map-examples.clj

;; Simplest use cases

;; Transform simple input
(map inc [1 2 3 4 5])

(map str [1 2 3 4 5])

(map clojure.string/lower-case ["COBOL" "Ada" "C"])

;; Extract simple input
(map :rating [{:frozen-product :ice-cream :flavour "Vanilla" :rating 4.5 }
              {:frozen-product :ice-cream :flavour "Chocolate" :rating 3.5}
              {:frozen-product :yoghurt :flavour "Cherry" :rating 4.0}])

;; > 1 collection - shortest 'wins'
(map str ["COBOL" "Ada" "C"] (range))

(map str ["COBOL" "Ada" "C"] (range 1))

;; reader # functions
(map #(str "Shiny new code from " %) ["Rust" "Reason" "Clojure"])

;; partial functions
(map (partial str "Old code from ") ["COBOL" "Ada" "C"])

;; use apply (in and out)

(map #(apply max %) [[1 2 3]
                     [4 5 6]
                     [7 8 9]])

(apply map vector [[:a :b :c]
                   [:d :e :f]
                   [:g :h :i]])
                   

;; transducer version
;; Used without a collection, map will create a transducer:
(def xf (map inc))

;; We can now apply this transducer to a sequence (handy when testing core.async)
(transduce xf conj (range 5))

;; threading example
(->> [{:frozen-product :ice-cream :flavour "Vanilla" :rating 4.5}
      {:frozen-product :ice-cream :flavour "Chocolate" :rating 3.5}
      {:frozen-product :yoghurt :flavour "Cherry" :rating 4.0}]
     (map :frozen-product)
     distinct)

;; oddities / misc
(clojure.set/map-invert {:a 1, :b 2})

;; lazy / eager
;; examples TBD