Clojure Koans Walkthrough

1. Introduction
2. Lists
3. Vectors
4. Sets
5. Maps
6. Functions
7. Conditionals
8. Higher Order Functions
9. Runtime Polymorphism
10. Lazy Sequences
11. Sequence Comprehensions
12. Creating Functions
13. Recursion
14. Destructuring
15. Refs
16. Atoms
17. Macros
18. Datatypes
19. Java Interop
20. Partition

Recommended Books

• ← Introduction
• Vectors →

2. Lists - Koans Walkthrough

This video covers the fundamental data structure of Lisp and Clojure: lists. Lisp stands for "LISt Processing", after all!

Here is the 02_lists.clj source code:

(meditations
  "Lists can be expressed by function or a quoted form"
  (= '(__ __ __ __ __) (list 1 2 3 4 5))

  "They are Clojure seqs (sequences), so they allow access to the first"
  (= __ (first '(1 2 3 4 5)))

  "As well as the rest"
  (= __ (rest '(1 2 3 4 5)))

  "The rest when nothing is left is empty"
  (= __ (rest '(100)))

  "And construction by adding an element to the front is simple"
  (= __ (cons :a '(:b :c :d :e)))

  "Conjoining an element to a list can be done in the reverse order"
  (= __ (conj '(:a :b :c :d :e) 0))

  "You can use a list like a stack to get the first element"
  (= __ (peek '(:a :b :c :d :e)))

  "Or the others"
  (= __ (pop '(:a :b :c :d :e)))

  "But watch out if you try to pop nothing"
  (= __ (try
          (pop '())
          (catch IllegalStateException e "No dice!")))

  "The rest of nothing isn't so strict"
  (= __ (try
          (rest '())
          (catch IllegalStateException e "No dice!"))))