Clojure

A quick introduction to the pragmatic LISP for the JVM

A pragmatic LISP for the JVM

A pragmatic LISP for the JVM

A pragmatic LISP for the JVM

A pragmatic LISP for the JVM

Why talk about this?

Complexity

1958

John McCarthy

1958!

A long time passes...

2007

Rich Hickey

Creating a practical LISP

• Immutable data structures
• Multicore concurrency
• Interop

Clojure key points

• Clojure is a LISP
• Runs anywhere Java does
• Offers a better FP abstraction

Allows developers to use sixty-year old technology!

Anatomy of a LISP

Lisp syntax

• Tiny core
• Much syntax sugar
• Such brackets
• Wow!

Names (Identifiers)

• f
• g
• my-function
• my-value
• tuple-2

Values

• 2
• "Two"
• \T
• :two
• (+ 1 1)

S-expressions

• (f)
• (str "Hello" "World")
• (+ 1 2 3)
• (+ 1 (+ 2 3))

Identity and Value

(def robert-rees "Robert Rees")

(def robert-rees "Rob Rees")

Identity and value

• (def a 1)
• (defn double [a] (* 2 a))
• (def double (fn [a] (* 2 a))

Behaviour

Laziness

Schrödinger's Cat

• (def box (atom (maybe-kill :cat)))
• (@a)

REPL

RE

Clojure conclusions

• Clojure is a LISP
• Runs anywhere Java does
• Offers a better FP abstraction
• Has an unconventional syntax

Allows developers to use sixty-year old technology!