How Languages Influence Each Other: Reflections on 14 Years of Apache Groovy

Languages have been influencing one another since the dawn of computer programming. There are families of languages: from Algol descendants with begin/end code blocks to those with curly braces such as C. Languages are not invented in a vacuum but are inspired by their predecessors. This session’s speaker, who has been working on Apache Groovy for the past 14 years, reflects on the influences that have driven the design of programming languages. In particular, Groovy’s base syntax was directly derived from Java’s but quickly developed its own flavor, adding closures, type inference, and operators from Ruby. Groovy also inspired other languages: C#, Swift, and JavaScript adopted Groovy’s null-safe navigation operator and the famous Elvis operator.

Transcript

1. REFLECTION ON 14 YEARS OF APACHE GROOVY HOW LANGUAGES INFLUENCE EACH OTHER GUILLAUME LAFORGE Apache Groovy PMC Chair Developer Advocate @ Google Cloud
 @glaforge
3. @glaforge INTRODUCTION APACHE GROOVY ▸ Groovy was born in 2003 ▸ Created by James Strachan & Bob McWhirter ▸ I joined the project in 2003 — 14 years ago! ▸ Currently serving as Chair of the Project Management Committee ▸ Groovy moved to the Apache Software Foundation to become Apache Groovy ▸ after Pivotal stopped funding the project 3
4. @glaforge INTRODUCTION DOWNLOAD NUMBERS TO BE PROUD OF 4 Move to ASF 30M+ for 2/3 of ’17 23M in 2016 13M in 2015 4.6M in 2014 3.2M in 2013 1.7 in 2012
5. C FAMILY MEMBER OF THE
6. @glaforge C FAMILY APACHE GROOVY PART OF THE C-FAMILY ▸ Like Java, C#, C++, JavaScript, D, Go, Swift, Dart, or even PHP :-)
 Apache Groovy is part of the C-family of languages ▸ Key syntax characteristics ▸ Curly braces delimit blocks ▸ No whitespace indentation ▸ Signatures of the form: type functionName(parameters) { … } ▸ Usual control structures: if/else, switch/case, for/while loops… 6
7. 99% JAVA Java’s close cousin
8. @glaforge C FAMILY JAVA’S CLOSE COUSIN — A VALID GROOVY PROGRAM TOO! 8 public class HelloWorld { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } public String greet() { return "Hello " + name; } public static void main(String[] args) { HelloWorld helloWorld = new HelloWorld(); helloWorld.setName("Groovy"); System.out.println(helloWorld.greet()); } }
9. @glaforge C FAMILY JAVA’S CLOSE COUSIN — MORE IDIOMATIC! 9 class HelloWorld { String name def greet() { "Hello ${name}" } } def helloWorld = new HelloWorld(name: "Groovy") println helloWorld.greet()
10. STRINGS MORE THAN FOUR
11. @glaforge STRINGS STRINGS INSPIRED BY PYTHON 11 {
12. @glaforge STRINGS STRINGS INSPIRED BY PYTHON 12 def firstname = 'Guillaume' def address = ''' 1st Main Street CA 94123 San Francisco '''
13. @glaforge STRINGS STRINGS INSPIRED BY PYTHON 13 def firstname = "Guillaume" def address = """ 1st Main Street CA 94123 San Francisco """
14. @glaforge STRINGS STRING INTERPOLATION SIMILAR TO RUBY AND ANT 14 def firstname = 'Guillaume' def lastname = 'Laforge' def name = "Mr ${firstname} $lastname"
15. @glaforge STRINGS LAZY INTERPOLATION 15 def a = 'a' def b = 'b' def s = "${a} ${-> b}" assert s == 'a b' a = 'x' b = 'y' assert s == 'a y'
16. @glaforge STRINGS MOAARRR STRINGS… 16 /The forward \/ slash/ $/ c:\ and /usr/local /$
17. CLOSURES FUNCTIONAL ORIENTATION
18. @glaforge FUNCTIONAL ORIENTATION A FIRST APPROACH WITH RUBY’S AND SMALLTALK SYNTAX 18 // smalltalk [ :a | a * 2 ] // ruby {| a | a * 2 }
19. @glaforge FUNCTIONAL ORIENTATION A FIRST APPROACH WITH RUBY’S AND SMALLTALK SYNTAX 19 def d = { a | a * 2 }
20. @glaforge FUNCTIONAL ORIENTATION PROBLEM WITH BINARY AND LOGICAL OR FOR DEFAULT PARAMETERS 20 def d = { a = 1 | 2 | a * 2 }
21. @glaforge FUNCTIONAL ORIENTATION ARROWS TO THE RESCUE! 21 def d = { a = 1 | 2 -> a * 2 }
22. CLASS INTERFACE, TRAIT, ABSTRACT
23. @glaforge OBJECT ORIENTATION CLASS, ABSTRACT CLASS, INTERFACE… LIKE JAVA 23 class A {} abstract class B {} interface C {}
24. @glaforge OBJECT ORIENTATION TRAITS… A LA SCALA THEATER 24 trait FlyingAbility { String fly() { "I'm flying!" } } trait SpeakingAbility { String speak() { "I'm speaking!" } } class Duck implements FlyingAbility, SpeakingAbility {} def d = new Duck() assert d.fly() == "I'm flying!" assert d.speak() == "I'm speaking!"
25. SMALLTALK
26. @glaforge SMALLTALK INFLUENCE NAMED PARAMETERS 26 // smalltalk Rectangle red width: 100 height: 200 // groovy rectangle red, width: 100, height: 200 def rectangle(Map m, Color r) { println "$m.width:$m.height $r" }
27. @glaforge SMALLTALK INFLUENCE COLLECTION METHODS NAMES 27 // map // #(1, 2, 3, 4) collect: [ :it | :it * 2 ] assert (1..4).collect { it * 2 } == [2, 4, 6, 8] // foldLeft // #(1, 2, 3) inject: 0 into: [ :count :item | count + item ] assert [1, 2, 3].inject(0) { count, item -> count + item } == 6
28. COLLECTIONS LISTS, MAPS…
29. @glaforge LISTS, MAPS, COLLECTIONS… NATIVE SYNTAX FOR DATA STRUCTURES 29 // python lists def list = [1, 2, 3] // like python maps // but with square brackets def map = [a: 1, b: 2]
30. INSPIRED OTHERS BUT APACHE GROOVY ALSO
32. CLOSURE TRAILING
33. @glaforge CLOSURE TRAILING CLOSURE 33 def unless(boolean b, Closure action) { if (!b) action() } unless(false, { println "xyz" }) unless(false) { println "xyz" }
34. KOTLIN THE ISLAND OF
35. @glaforge KOTLIN KOTLIN, A MIX OF JAVA, SCALA, AND… APACHE GROOVY ▸ Kotlin adopted ▸ the syntax of Groovy closures and its ‘it’ default parameter, ▸ the notation for trailing closures ▸ Groovy’s builder concept ▸ Kotlin’s data classes, delegate and lazy mechanisms, follow Groovy’s @Immutable, @Delegate and @Lazy transformations ▸ Method name convention based operator overloading 35
36. @glaforge KOTLIN KOTLIN, A MIX OF JAVA, SCALA, AND… APACHE GROOVY ▸ Kotlin adopted Groovy’s optional semicolons ▸ Groovy’s Elvis operator ▸ Groovy’s null-safe navigation operator ▸ but with a different approach with non/nullable types ▸ Groovy’s interpolated strings (dollar placeholders with & without curly braces) ▸ Groovy’s import aliasing 36
37. @glaforge KOTLIN GROOVY’S BUILDER 37 html { head { title ("a title") } body { h1 ("first header") p ("a paragraph") } } html { head { title {+"a title"} } body { h1 {+"first header"} p {+"a paragraph"} } }
38. NAVIGATION NULL-SAFE
39. @glaforge INSPIRED OTHERS NULL-SAFE NAVIGATION OPERATOR 39
40. @glaforge INSPIRED OTHERS NULL-SAFE NAVIGATION OPERATOR 40 def name = book?.author?.name
41. ELVIS CALLING
42. @glaforge INSPIRED OTHERS THE ELVIS OPERATOR 42
43. @glaforge INSPIRED OTHERS THE ELVIS OPERATOR 43 def name = book?.author?.name ?: 'Unknown'
44. RANGES
45. @glaforge INSPIRED OTHERS RANGES 45 // Ruby style initially // 1..4 == [1, 2, 3, 4] and 1...4 == [1, 2, 3] // ..< is more visual assert 1..4 == [1, 2, 3, 4] assert 1..<4 == [1, 2, 3] // Swift adopted 1..<4
46. SPACESHIP AN OPERATOR FLYING LIKE A
47. @glaforge INSPIRED OTHERS THE SPACESHIP OPERATOR 47 assert (1 <=> 1) == 0 assert (1 <=> 2) == -1 assert (2 <=> 1) == 1 assert ('a' <=> 'z') == -1
48. SUMMARY GUILLAUME LAFORGE Apache Groovy PMC Chair Developer Advocate @ Google Cloud
 @glaforge
49. INSPIRATION IS A TWO-WAY STREET Be influenced and influence others
50. NO LANGUAGE IS PERFECT But they’re all improving!
51. THANKS Q & A GUILLAUME LAFORGE Apache Groovy PMC Chair Developer Advocate @ Google Cloud
 @glaforge