Do Things: A Clojure Crash Course | Clojure for the Brave and True

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• Clojure’s most salient characteristic is that it is a Lisp

• Clojure recognizes two kinds of structures: Literal representations of data structures (like numbers, strings, maps, and vectors) Operations

• Operations are how you do things. All operations take the form opening parenthesis, operator, operands, closing parenthesis:

• Clojure uses whitespace to separate operands, and it treats commas as whitespace

• if This is the general structure for an if expression: (if boolean-form then-form optional-else-form)

• The do operator lets you wrap up multiple forms in parentheses and run each of them. Try the following in your REPL: (if true (do (println "Success!") "By Zeus's hammer!") (do (println "Failure!") "By Aquaman's trident!")) ; => Success! ; => "By Zeus's hammer!"

• The when operator is like a combination of if and do, but with no else branch. Here’s an example: (when true (println "Success!") "abra cadabra") ; => Success! ; => "abra cadabra"

• Use when if you want to do multiple things when some condition is true, and you always want to return nil when the condition is false.

• You can check if a value is nil with the appropriately named nil? function:

• Both nil and false are used to represent logical falsiness

• (if "bears eat beets" "bears beets Battlestar Galactica") ; => "bears beets Battlestar Galactica" (if nil "This won't be the result because nil is falsey" "nil is falsey") ; => "nil is falsey"

• Clojure’s equality operator is =:

• You use def to bind a name to a value in Clojure:

• (def failed-protagonist-names ["Larry Potter" "Doreen the Explorer" "The Incredible Bulk"]) failed-protagonist-names ; => ["Larry Potter" "Doreen the Explorer" "The Incredible Bulk"]

• Clojure comes with a handful of data structures that you’ll use the majority of the time

• All of Clojure’s data structures are immutable, meaning you can’t change them in place

• Clojure has pretty sophisticated numerical support

• Suffice it to say, Clojure will merrily handle pretty much anything you throw at it.

• Maps are similar to dictionaries or hashes

• The two kinds of maps in Clojure are hash maps and sorted maps