clojure-koans/src/koans/02_lists.clj

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2010-02-20 15:30:24 +00:00
(meditations
"Lists can be expressed by function or a quoted form"
(= '(__ __ __ __ __) (list 1 2 3 4 5))
2010-02-20 15:30:24 +00:00
"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!"))))