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Two ways to bind values to names:

def — top-level (global) binding:

(def pi 3.14159)
(def greeting "Hello")

let — local, lexically-scoped binding:

(let [x 10
      y 20]
  (+ x y))      ; 30

let takes a vector of [name value name value ...] and a body. The bindings are visible only inside the body.

Clojure has these atomic types:

• numbers: 42, 3.14, 1/3 (ratio!)
• strings: "hello"
• characters: \a, \space
• keywords: :name, :age — like enum tags, used heavily as map keys
• symbols: bare names like pi, greeting
• nil: nil (also represents false in conditionals)
• booleans: true, false

Reading stdin: (read-line) reads one line. Convert with Integer/parseInt, Double/parseDouble (interop with Java).