Live coding session code: https://github.com/olimsaidov/clojure-demo-chat

1. Clojure –
есть ли жизнь после Java

2. Clojure –
есть ли жизнь после Java
Ruby
PHP
Scala
Python
Javascript
Go
...
...

3. Парадигмы
Declarative
SQLDatalog
Prolog
Logic
Functional
ML
Lisp
CLOS
Object-Oriented
Java
C++
C
Pascal
Procedural
Bash
Imperative

4. Что такое Clojure
• Язык общего назначения
• Запускается на JVM
• Функциональный Lisp
• С учетом многопоточности

5. Сильные стороны
• Динамическая разработка (REPL)
• Иммутабельность по умолчанию
• Lisp (compact, code-as-data, macros)
• Concurrency (atoms, software transactional memory)
• Выполняется на JVM (access to the java ecosystem)

6. * https://leonid.shevtsov.me/post/companies-that-are-using-clojure/

7. Clojure Basics

8. Примитивы
"Hello" ;string
1 ;int
1.2 ;float
false ;boolean
[1 2 3] ;vector
(1 2 3) ;list
{:a 1 :b 2} ;hash-map
:abc ;keyword
#{1 2 3} ;set
!8

9. Вызов функции
(function-name arg1 arg2 arg3)
Имя функции или макроса
Аргументы
s-expression

10. Functions
(str "Hel" "lo") ; => "Hello"
(+ 1 1) ; => 2
(- 2 1) ; => 1
(* 1 2) ; => 2
(/ 2 1) ; => 2
(= 1 1) ; => true
(= 2 1) ; => false

11. (< 1 2) ; => true
(> 3 2 1) ; => true
(and true false) ; => false
(or true false) ; => true
(if (> 1 2)
"good"
"bad") ; => "bad"
Functions

12. (map inc [1 2 3]) ; => (2 3 4)
(filter even? [1 2 3 4]) ; => (2 4)
(reduce + [1 2 3]) ; => 6
(concat [1 2] [3 4]) ; => (1 2 3 4)
(conj [1 2] 3) ; => [1 2 3]
(assoc {:a 1} :b 2) ; => {:a 1 :b 2}
(dissoc {:a 1 :b 2} :b) ; => {:a 1}
Functions

13. (defn say-hello [name]
(str "Hello " name))
(say-hello "World") ; => "Hello World"
(map (fn [a] (* a a))
[1 2 3 4]) ; => (1 4 9 16)
Functions

14. ( -> some-value
(coerce)
(validate)
(save))
(save (validate (coerce some-value)))
Macros

15. (defmacro infix
[infixed]
(list (second infixed)
(first infixed)
(last infixed)))
(infix (1 + 1)) ; => 1
Macros

16. Vars and Bindings
(def word "hi")
(def n 3)
(repeat n word) ; => ("hi" "hi" "hi")
(let [a 2
b 3]
(+ a b)) ; => 5

17. Java Interoperation
(import java.util.Date)
(Date.) ; => <a date object>
(.getTime (Date.)) ; => 1534589618419
(System/currentTimeMillis) ; => 1534589705587

18. Live Coding

19. Learn Clojure
• braveclojure.com
• clojurecourse.by