Clojure Koans 3 Lists Notebook

{:hello (clojure-version)}

;; "Lists can be expressed by function or a quoted form"

(= '(1 2 3 4 5) (list 1 2 3 4 5))

;; skill 3001: create a list via "quoted form"

;; skill 3002: create a list via the `list` function and some # of arguments

;; question 3001: Can an empty list be created via `(list)` (ie. call to `list` w/ zero arguments)

;; "They are Clojure seqs (sequences), so they allow access to the first"

(= 1 (first '(1 2 3 4 5)))

;; question 3002: Is a list in Clojure a sequence? Why or why not?

;; skill 3003: Get the first item/element (?) of a list by using the `first` function

;; "As well as the rest"

(= '(2 3 4 5) (rest '(1 2 3 4 5)))

;; skill 3004: Get all items of a list except for the first by using the `rest` function

;; "Count your blessings"

(= 3 (count '(dracula dooku chocula)))

;; skill 3005: Measure the quantity of items in a list using the `count` function

;; "Before they are gone"

(= 0 (count '()))

;; "The rest, when nothing is left, is empty"

(= '() (rest '(100)))

;; "Construction by adding an element to the front is easy"

(= '(:a :b :c :d :e) (cons :a '(:b :c :d :e)))

;; skill 3006: Append an item to the front of a list in Clojure by using the `cons` function. (confirm wording 2021_04_25)

;; question 3003: What are the differences between the `cons` and `conj` functions?

;; "Conjoining an element to a list isn't hard either"

(= '(:e :a :b :c :d) (conj '(:a :b :c :d) :e))

;; skill 3007: Append an item to the front of a list in Clojure by using the `conj` function (confirm wording 2021_04_25)

;; "You can use a list like a stack to get the first element"

(= :a (peek '(:a :b :c :d :e)))

;; skill 3008: Inspect/Return the first element of a list by using the stack function `peek`

;; "Or the others"

(= '(:b :c :d :e) (pop '(:a :b :c :d :e)))

;; skill 3009: Inspect/Return all elements of a list but the first by using the stack function `pop`

;; "But watch out if you try to pop nothing"

(= "No dice!" (try

                 (pop '())

                 (catch IllegalStateException e

                   "No dice!")))

;; skill 3010: Run code that will throw an exception/error and handle it "gracefully" inside of a "try-catch" block by using `try` and `catch`

;; "The rest of nothing isn't so strict"

(= '() (try

          (rest '())

          (catch IllegalStateException e

            "No dice!")))

;; question 3004: What is the difference between an error and an exception in Clojure?

;; question 3005: What things in Clojure are identical to Java?

;; question 3006: What things in Clojure are identical to other LISPs?

;; question 3007: What are the primary differences between Clojure and Java?

;; question 3008: What are the primary differences between Clojure and other LISPs?

;; question 3009: What are the top 25 most common "gotchas" in Clojure?

;; question 3010: Conceptually speaking, what do most learners of Clojure struggle with / what are the biggest pain points?