Clojure Koans 17 Atoms Notebook

{:hello (clojure-version)}

(def atomic-clock (atom 0))

;; "Atoms are like refs"

(= 0 @atomic-clock)

;; question 17001: What are the similarities and differences between atoms and refs?

;; question 17002: How do atoms in Clojure compare with variables in other languages?

;; skill 17001: Create an atom and bind it to memory (?) by using `atom` and `def`

;; skill 17002: Access the value stored in an atom (?) by dereferencing (?) it with the `@` prefix/shorthand (?)

;; "You can change at the swap meet"

(= 1 (do

         (swap! atomic-clock inc)

         @atomic-clock))

;; skill 17003: Update/modify (?) an atom by using the `swap!` macro/function (?)

;; "Keep taxes out of this: swapping requires no transaction"

(= 5 (do

         (swap! atomic-clock + 4)

         @atomic-clock))

;; skill 17004: Update/modify (?) an atom by using the `swap!` macro/function (?) and an argument

;; "Any number of arguments might happen during a swap"

(= 20 (do

          (swap! atomic-clock + 1 2 3 4 5)

          @atomic-clock))

;; skill 17005: Update/modify (?) an atom by using the `swap!` macro/function (?) and multiple arguments

;; "Atomic atoms are atomic"

(= 20 (do

          (compare-and-set! atomic-clock 100 :fin)

          @atomic-clock))

;; description: This Koan compares atomic-clock (which is currently 20) with 100, and since this comparison is false, atomic-clock is not changed to `:fin`. 

;; skill 17006: Check to see if an atom has a certain value, and, if so, change its value by using the `compare-and-set!` macro/function (?)

;; "When your expectations are aligned with reality, things proceed that way"

(= :fin (do

            (compare-and-set! atomic-clock 20 :fin)

            @atomic-clock))