Short Tour Of Clojure

Transcript

1. Lead Consultant www.ajira.tech Tamizhvendan S Passionate, Pragmatic and Polyglot Programmer https://www.demystifyfp.com tamizhvendan (short-tour (of (clojure)))
2. Credits: https://twitter.com/andreasdotorg/status/570190592610832384
5. Credits: https://github.com/tallesl/Rich-Hickey-fanclub Simple Made Easy Hammock Driven Development The Value of Values Effective Programs
6. Credits: https://www.artsy.net/artwork/brian-kernighan-hello-world
7. Hello World in three languages printf("Hello, World!\n"); C System.out.println("Hello, World"); Java println("Hello, World") Scala
8. Hello World Requirements 1. A String Representation 2. Function/Method
9. function (argument) Function/Method Invocation
10. function (argument) Clojure’s way! (function argument)
11. Hello World in Clojure (println "Hello, World!")
12. (println "Hello, World!") function argument whitespace Clojure Syntax
13. Functions with multiple arguments printf("hello, %s\n", "World!"); C System.out.printf("Hello, %s\n", "World!"); Java printf("Hello, %s\n", "World!") Scala
14. function (argument1, argument2) Function/Method Invocation
15. (function argument1, argument2) Clojure’s way! function (argument1, argument2)
16. (function argument1, argument2) (function argument1 argument2) optional Clojure’s way!
17. (function argument1 argument2 argument3 …) Clojure’s way!
18. Consistent Syntax 1. Adding the numbers one, two, three & four 2. Converting an integer to a string 3. Concatenating two strings 4. Conditional Operator
19. Adding the numbers one, two, three & four 1 + 2 + 3 + 4 Converting an integer to a string String.valueOf(1) Concatenating two strings "Hello, ".concat("World!")
20. 1 + 2 + 3 + 4 function function function argument1 argument2 argument3 argument4 Infix Notation
21. method String.valueOf(1) ClassName argument invoke function Prefix Notation
22. method "Hello, ".concat("World!") Object argument invoke function Prefix Notation
23. argument2 true ? "truthy" : "falsy" argument1 separator function argument3 Conditional Operator
24. function argument2 argument4 argument1 argument3 (+ 1 2 3 4) Clojure Syntax 1 + 2 + 3 + 4
25. (String/valueOf 1) function argument1 class name static method argument(s) to the static method Clojure Syntax String.valueOf(1)
26. (. "Hello, " concat "World!") function argument1 argument2 argument3 instance instance method argument(s) to the instance method special form Clojure Syntax "Hello, ".concat("World!")
27. (if true "truthy" "falsy") function argument1 argument2 argument3 boolean value value1 value2 special form Clojure Syntax true ? "truthy" : "falsy"
28. Clojure Syntax
29. Clojure Form A structure that the Clojure compiler recognise.
30. Types of Clojure Forms Atomic Data Type - Literals "Hello, World" 1 1.2 true nil \a :keyword symbol false
31. Types of Clojure Forms Collection - Literals [1 "2" 3] '(1 1.2 1.5) {:one 1 :two 2 :three 3} #{1 2 3}
32. Types of Clojure Forms Expressions (function invocation) (println "Hello, World!") (println "Hello," "World!") (+ 1 2 3 4) (String/valueOf 1) (. "Hello, " concat "World!")
33. Literals evaluate to itself user!=> "Hello, World" "Hello, World" user!=> 1 1
34. Expression always return a value user!=> (println "Hello, Clojure!") Hello, Clojure! nil  output of println function  return value of println function
35. Forms can be nested (println "1 + 1 =" (+ 1 1))
36. Clojure Evaluation Model (println "1 + 1 =" (+ 1 1)) left to right
37. Clojure Evaluation Model (println "1 + 1 =" (+ 1 1)) An expression begins with “(“
38. Clojure Evaluation Model (println "1 + 1 =" (+ 1 1)) function symbol println is a variadic function defined in the clojure.core namespace.
39. Clojure Evaluation Model (println "1 + 1 =" (+ 1 1)) argument1 string literal literals evaluate to itself
40. Clojure Evaluation Model (println "1 + 1 =" (+ 1 1)) An expression begins with “(“ argument2
41. Clojure Evaluation Model (println "1 + 1 =" (+ 1 1)) function symbol + is a variadic function defined in the clojure.core namespace.
42. Clojure Evaluation Model (println "1 + 1 =" (+ 1 1)) argument1 integer literal literals evaluate to itself
43. Clojure Evaluation Model (println "1 + 1 =" (+ 1 1)) argument2 integer literal literals evaluate to itself
44. Clojure Evaluation Model (println "1 + 1 =" (+ 1 1)) An expression ends with “)“
45. Clojure Evaluation Model (println "1 + 1 =" 2) All expressions return a value
46. Clojure Evaluation Model (println "1 + 1 =" 2) An expression ends with “)“
47. Clojure Evaluation Model (println "1 + 1 =" 2) user!=> (println "1 + 1 =" (+ 1 1)) 1 + 1 = 2 nil  output of println function  return value of println function
48. Clojure Evaluation Model Deviations Special Forms if . def let quote var fn loop recur Macros when condp -> ->> Macros are programs that write programs! try do
49. Summary f(x) translates to (f x) f(x, y) translates to (f x y) o.m(x) translates to (. o m x) 1 + 2 + 3 + 4 translates to (+ 1 2 3 4) Prefix Notation
50. Demo!
51. Let’s start!