Groovy in the light of Java 8 -- Devoxx 2014

@glaforge #devoxx #groovylang Groovy in the light of Java 8
Guillaume Laforge Groovy project manager

@glaforge #devoxx #groovylang Stay up-to-date Groovy Weekly newsletter (every Tuesday)
  http://beta.groovy-lang.org/groovy-weekly.html 2

@glaforge #devoxx #groovylang Goal of this talk

@glaforge #devoxx #groovylang A recurring question… Do we still need
Groovy now that we have Java 8? 4

@glaforge #devoxx #groovylang To those who said no… 5

@glaforge #devoxx #groovylang But more precisely… • Will Java lambdas
replace Groovy closures? • What are the differences between them? • Will Groovy support all the new Java 8 language constructs? • lambdas, default methods, method references… • How Groovy developers can beneﬁt from Java 8? • What does Groovy offer beyond Java 8? 6

@glaforge #devoxx #groovylang What about redundancy? • Closures • Traits
• Truth & null handling • Functional with collections • Method closures • Lambdas • Default methods • Optional • Stream API • Method references 7

@glaforge #devoxx #groovylang What’s new in Java 8?

This is not a Java 8 crash courses with all
the details :-)

This is not a Java 8 crash courses with all
the details :-) We want to understand the implications with regards to Groovy

@glaforge #devoxx #groovylang What’s new in Java 8? • New
syntax • Streams • Proﬁles • Security enhancements • JavaFX • Tools • i18n • Date / time API • Nashorn / JavaScript • Pack200 • IO / NIO improvements • New utility classes • JDBC • Networking • Concurrency • JAXP • Hotspot • Java Mission Control 10

@glaforge #devoxx #groovylang What’s new in Java 8? • New
syntax • Streams • Proﬁles • Security enhancements • JavaFX • Tools • i18n • Date / time API • Nashorn / JavaScript • Pack200 • IO / NIO improvements • New utility classes • JDBC • Networking • Concurrency • JAXP • Hotspot • Java Mission Control 10 Great concise resource with the whole list: http://bit.ly/new-in-java-8

@glaforge #devoxx #groovylang New Java 8 syntax

@glaforge #devoxx #groovylang New Java 8 syntax constructs • Lambda
expressions • Method references • Static & default methods in interfaces • Repeating annotations • Annotations on types • Improved type inference • Method parameter reﬂection 12

@glaforge #devoxx #groovylang New Java 8 syntax constructs • Lambda
expressions • Method references • Static & default methods in interfaces • Repeating annotations • Annotations on types • Improved type inference • Method parameter reﬂection 13

@glaforge #devoxx #groovylang Lambda expressions 15 double highestScore = students
.filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max();

.filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max(); Coercion into a Predicate « functional interface »

.filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max(); There’s no function type!

.filter(Student s -> s.getGradYear() == 2011) .map(Student s -> s.getScore()) .max(); Pipeline being built Single pass!

.findAll { it.gradYear == 2011 } .collect { it.score} .max()

.findAll { it.gradYear == 2011 } .collect { it.score} .max() In Groovy, that would be…

.findAll { it.gradYear == 2011 } .collect { it.score} .max() Drawback: intermediary data structures Unless you use iterator variants

.findAll { it.gradYear == 2011 } .collect { it.score} .max()

.filter { Student s -> s.gradYear == 2011 } .map { Student s -> s.getScore() } .max()

.filter { Student s -> s.gradYear == 2011 } .map { Student s -> s.getScore() } .max() Same coercion to Predicate but works for abstract classes too

.filter { Student s -> s.gradYear == 2011 } .map { Student s -> s.getScore() } .max()

@glaforge #devoxx #groovylang The various lambda syntaxes 19 String name
-> name.length() (int left, int right) -> left + right (String left, String sep, String right) -> { System.out.println(left + sep + right) }

-> name.length() (int left, int right) -> left + right (String left, String sep, String right) -> { System.out.println(left + sep + right) } One parameter: no parens Expression on right: no curly

-> name.length() (int left, int right) -> left + right (String left, String sep, String right) -> { System.out.println(left + sep + right) } Parentheses required for more that one parameter

-> name.length() (int left, int right) -> left + right (String left, String sep, String right) -> { System.out.println(left + sep + right) } Statements require curly braces Return keyword required if non-void returning

-> name.length() (int left, int right) -> left + right (String left, String sep, String right) -> { System.out.println(left + sep + right) } Clever type inference can help get rid of parameter type declarations

@glaforge #devoxx #groovylang Closures vs lambdas 20 IntStream.range(1, 100).forEach(s ->
System.out.println(s)); Files.lines(Paths.get('README.adoc')) .map(it -> it.toUpperCase()) .forEach(it -> System.out.println(it));

System.out.println(s)); Files.lines(Paths.get('README.adoc')) .map(it -> it.toUpperCase()) .forEach(it -> System.out.println(it)); IntStream.range(1, 100).forEach { println it } Files.lines(Paths.get('README.adoc')) .map { it.toUpperCase() } .forEach { println it }

System.out.println(s)); Files.lines(Paths.get('README.adoc')) .map(it -> it.toUpperCase()) .forEach(it -> System.out.println(it)); IntStream.range(1, 100).forEach { println it } Files.lines(Paths.get('README.adoc')) .map { it.toUpperCase() } .forEach { println it } Use Groovy closures wherever you pass lambdas in Java 8

System.out.println(s)); Files.lines(Paths.get('README.adoc')) .map(it -> it.toUpperCase()) .forEach(it -> System.out.println(it)); IntStream.range(1, 100).forEach { println it } Files.lines(Paths.get('README.adoc')) .map { it.toUpperCase() } .forEach { println it } Groovy coerces to SAM types (Single Abstract Method)

System.out.println(s)); Files.lines(Paths.get('README.adoc')) .map(it -> it.toUpperCase()) .forEach(it -> System.out.println(it)); IntStream.range(1, 100).forEach { println it } Files.lines(Paths.get('README.adoc')) .map { it.toUpperCase() } .forEach { println it }

@glaforge #devoxx #groovylang Beyond: Closure default parameters 21 def mult
= { int a, int b = 10 -> a * b } assert mult(2, 3) == 6 assert mult(5) == 50

@glaforge #devoxx #groovylang Beyond: Closure default parameters 21 def mult
= { int a, int b = 10 -> a * b } assert mult(2, 3) == 6 assert mult(5) == 50 Default value if the parameter is not specified

@glaforge #devoxx #groovylang Beyond: Duck typing polymorphism 22 def adder
= { a, b -> a + b } assert adder(100, 200) == 300 assert adder('X', 'Y') == 'XY'

@glaforge #devoxx #groovylang Beyond: Duck typing polymorphism 22 def adder
= { a, b -> a + b } assert adder(100, 200) == 300 assert adder('X', 'Y') == 'XY' Works both for numbers and for strings

Builders

Builders What would Java lambda builders look like?

Builders What would Java lambda builders look like? Aren’t Groovy
builders more powerful?

@glaforge #devoxx #groovylang Lambda-based builders uglier and less 24 MarkupBuilder
pom = new XmlMarkupBuilder() pom.el("modelVersion", "4.0.0"); pom.el("groupId", "com.github"); pom.el("artifactId", "lambda-builder"); pom.el("version", "1.0-SNAPSHOT"); pom.el("dependencies", () -> { pom.el("dependency", () -> { pom.el("groupId", "junit"); pom.el("artifactId", "junit"); pom.elx("version", "4.11"); }); pom.el("dependency", () -> { pom.el("groupId", "commons-beanutils"); pom.el("artifactId", "commons-beanutils"); pom.elx("version", "1.7.0"); }); });

pom = new XmlMarkupBuilder() pom.el("modelVersion", "4.0.0"); pom.el("groupId", "com.github"); pom.el("artifactId", "lambda-builder"); pom.el("version", "1.0-SNAPSHOT"); pom.el("dependencies", () -> { pom.el("dependency", () -> { pom.el("groupId", "junit"); pom.el("artifactId", "junit"); pom.elx("version", "4.11"); }); pom.el("dependency", () -> { pom.el("groupId", "commons-beanutils"); pom.el("artifactId", "commons-beanutils"); pom.elx("version", "1.7.0"); }); }); Repeated « pom »: No delegate like in Groovy’s closures

pom = new XmlMarkupBuilder() pom.el("modelVersion", "4.0.0"); pom.el("groupId", "com.github"); pom.el("artifactId", "lambda-builder"); pom.el("version", "1.0-SNAPSHOT"); pom.el("dependencies", () -> { pom.el("dependency", () -> { pom.el("groupId", "junit"); pom.el("artifactId", "junit"); pom.elx("version", "4.11"); }); pom.el("dependency", () -> { pom.el("groupId", "commons-beanutils"); pom.el("artifactId", "commons-beanutils"); pom.elx("version", "1.7.0"); }); }); Zero-arg lamdas not as lean

pom = new XmlMarkupBuilder() pom.el("modelVersion", "4.0.0"); pom.el("groupId", "com.github"); pom.el("artifactId", "lambda-builder"); pom.el("version", "1.0-SNAPSHOT"); pom.el("dependencies", () -> { pom.el("dependency", () -> { pom.el("groupId", "junit"); pom.el("artifactId", "junit"); pom.elx("version", "4.11"); }); pom.el("dependency", () -> { pom.el("groupId", "commons-beanutils"); pom.el("artifactId", "commons-beanutils"); pom.elx("version", "1.7.0"); }); }); Generic method + string: No dynamic method

@glaforge #devoxx #groovylang Neater Groovy builder! 25 def pom =
new PomBuilder().project { modelVersion "4.0.0" groupId "com.github" artifactId "lambda-builder" version "1.0-SNAPSHOT" dependencies { dependency { groupId "junit" artifactId "junit" version "4.11" } dependency { groupId "commons-beanutils" artifactId "commons-beanutils" version "1.7.0" } } }

Aren’t Groovy builders more readable and lean?

@glaforge #devoxx #groovylang To those who said no… 27

Memoization

@glaforge #devoxx #groovylang Closure and method memoization 29 def fib2
= { long n -> if (n < 2) 1 else call(n - 1) + call(n - 2) }.memoize()

@glaforge #devoxx #groovylang Closure and method memoization 29 def fib2
= { long n -> if (n < 2) 1 else call(n - 1) + call(n - 2) }.memoize() Closures: memoize()

@glaforge #devoxx #groovylang Closure and method memoization 29 @Memoized long
fib(long n) { if (n < 2) 1 else fib(n - 1) + fib(n - 2) } def fib2 = { long n -> if (n < 2) 1 else call(n - 1) + call(n - 2) }.memoize() Closures: memoize()

@glaforge #devoxx #groovylang Closure and method memoization 29 @Memoized long
fib(long n) { if (n < 2) 1 else fib(n - 1) + fib(n - 2) } def fib2 = { long n -> if (n < 2) 1 else call(n - 1) + call(n - 2) }.memoize() Closures: memoize() Methods: memoization AST transformation

Tail recursion

@glaforge #devoxx #groovylang Closure and method tail recursion 31 def
fact = { n, accu = 1G -> if (n < 2) accu else fact.trampoline(n - 1, n * accu) }.trampoline()

@glaforge #devoxx #groovylang Closure and method tail recursion 31 def
fact = { n, accu = 1G -> if (n < 2) accu else fact.trampoline(n - 1, n * accu) }.trampoline() Closures: Tail recursion with trampoline()

@glaforge #devoxx #groovylang Closure and method tail recursion 31 @groovy.transform.TailRecursive
def fact(n, accu = 1G) { if (n < 2) accu else fact(n - 1, n * accu) } def fact = { n, accu = 1G -> if (n < 2) accu else fact.trampoline(n - 1, n * accu) }.trampoline() Closures: Tail recursion with trampoline()

@glaforge #devoxx #groovylang Closure and method tail recursion 31 @groovy.transform.TailRecursive
def fact(n, accu = 1G) { if (n < 2) accu else fact(n - 1, n * accu) } def fact = { n, accu = 1G -> if (n < 2) accu else fact.trampoline(n - 1, n * accu) }.trampoline() Closures: Tail recursion with trampoline() Methods: Tail recursion with @TailRecursive transformation

@glaforge #devoxx #groovylang Method references 32 button.setOnAction(event -> System.out.println(event));

@glaforge #devoxx #groovylang Method references 32 button.setOnAction(event -> System.out.println(event)); button.setOnAction(System.out::println);

@glaforge #devoxx #groovylang Method references — 3 main cases •
Three main cases: 33 instance::instanceMethod SomeClass::staticMethod SomeClass::instanceMethod

@glaforge #devoxx #groovylang Method references — 3 main cases •
Three main cases: 33 instance::instanceMethod SomeClass::staticMethod SomeClass::instanceMethod Not covered by Groovy method closures yet!

@glaforge #devoxx #groovylang Groovy’s method closure 34 instance.&instanceMethod SomeClass.&staticMethod SomeClass.&instanceMethod

@glaforge #devoxx #groovylang Groovy’s method closure 34 instance.&instanceMethod SomeClass.&staticMethod SomeClass.&instanceMethod
Choices: Adopt :: Deprecate .& Enhance .&

@glaforge #devoxx #groovylang Static methods in interfaces • You can
put static utility methods in interfaces,   instead of in companion classes (like « Collections ») 35 public interface Stream<T> { // ... static <T> Stream<T> empty() { return new Stream<T> { ... } } }

@glaforge #devoxx #groovylang Default methods in interfaces • Deﬁne default
behavior • possibly to enrich existing interfaces 36 public interface Stream<T> { // ... default Builder<T> add(T t) { ... } }

@glaforge #devoxx #groovylang Groovy Traits • Like interfaces, but with
method bodies • similar to Java 8 interface default methods • Elegant way to compose behavior • multiple inheritance without the « diamond » problem • Traits can also be stateful • traits can have properties like normal classes • Compatible with static typing and static compilation • class methods from traits also visible from Java classes • Also possible to implement traits at runtime 37

@glaforge #devoxx #groovylang Simple trait 38 trait FlyingAbility { String
fly() { "I'm flying!" } } class Bird implements FlyingAbility {} def b = new Bird() assert b.fly() == "I'm flying!"

@glaforge #devoxx #groovylang Trait with state 39 trait Named {
String name } class Bird implements Named {} def b = new Bird(name: 'Colibri') assert b.name == 'Colibri'

@glaforge #devoxx #groovylang Multiple inheritance 40 trait KiteSurfer { String
surf() { 'kite' } } trait WebSurfer { String surf() { 'web' } } class Person { String name } class Hipster extends Person implements KiteSurfer, WebSurfer {} def h = new Hipster() assert h.surf() == 'web'

Annotations on types Repeating annotations

@glaforge #devoxx #groovylang Repeating annotations 42 @Schedule(dayOfMonth = "last") @Schedule(dayOfWeek
= "Fri", hour = 23) public void doPeriodicCleanup() { ... }

= "Fri", hour = 23) public void doPeriodicCleanup() { ... } @Schedule annotation repeated twice

= "Fri", hour = 23) public void doPeriodicCleanup() { ... } @Repeatable(Schedules.class) public @interface Schedule { String dayOfMonth() default "first"; String dayOfWeek() default "Mon"; int hour() default 12; }

= "Fri", hour = 23) public void doPeriodicCleanup() { ... } @Repeatable(Schedules.class) public @interface Schedule { String dayOfMonth() default "first"; String dayOfWeek() default "Mon"; int hour() default 12; } Container annotation for the repeated annotationd

= "Fri", hour = 23) public void doPeriodicCleanup() { ... } @Repeatable(Schedules.class) public @interface Schedule { String dayOfMonth() default "first"; String dayOfWeek() default "Mon"; int hour() default 12; } public @interface Schedules { Schedule[] value(); }

= "Fri", hour = 23) public void doPeriodicCleanup() { ... } @Repeatable(Schedules.class) public @interface Schedule { String dayOfMonth() default "first"; String dayOfWeek() default "Mon"; int hour() default 12; } public @interface Schedules { Schedule[] value(); } The container annotation iteself

= "Fri", hour = 23) public void doPeriodicCleanup() { ... } @Repeatable(Schedules.class) public @interface Schedule { String dayOfMonth() default "first"; String dayOfWeek() default "Mon"; int hour() default 12; } public @interface Schedules { Schedule[] value(); } Not yet supported

@glaforge #devoxx #groovylang Annotations on types • Everywhere you can
put a type, you can put an annotation 43 @NonNull String name; email = (@Email String) input; List<@NonNull String> names; new @Interned MyObject(); void monitorTemperature() throws @Critical TemperatureException { ... } class UnmodifiableList<T> implements @Readonly List<@Readonly T> {...}

put a type, you can put an annotation 43 @NonNull String name; email = (@Email String) input; List<@NonNull String> names; new @Interned MyObject(); void monitorTemperature() throws @Critical TemperatureException { ... } class UnmodifiableList<T> implements @Readonly List<@Readonly T> {...} Not yet supported

put a type, you can put an annotation 43 @NonNull String name; email = (@Email String) input; List<@NonNull String> names; new @Interned MyObject(); void monitorTemperature() throws @Critical TemperatureException { ... } class UnmodifiableList<T> implements @Readonly List<@Readonly T> {...} Imagine the potential for targets for local AST transformations?

put a type, you can put an annotation 43 @NonNull String name; email = (@Email String) input; List<@NonNull String> names; new @Interned MyObject(); void monitorTemperature() throws @Critical TemperatureException { ... } class UnmodifiableList<T> implements @Readonly List<@Readonly T> {...}

@glaforge #devoxx #groovylang Groovy compile-time meta-annotations 44 @Service @Transactional class
MyTransactionalService {}

@glaforge #devoxx #groovylang Groovy compile-time meta-annotations 44 @Service @Transactional class
MyTransactionalService {} import groovy.transform.AnnotationCollector @Service @Transactional @AnnotationCollector public @interface TransactionalService {}

@glaforge #devoxx #groovylang Groovy compile-time meta-annotations 44 import groovy.transform.AnnotationCollector @Service
@Transactional @AnnotationCollector public @interface TransactionalService {} @TransactionalService class MyTransactionalService {}

@Transactional @AnnotationCollector public @interface TransactionalService {} @TransactionalService class MyTransactionalService {} Can handle parameters (even conflicting), or you can create your own « processor »

@Transactional @AnnotationCollector public @interface TransactionalService {} @TransactionalService class MyTransactionalService {}

@glaforge #devoxx #groovylang New Java 8 APIs

Date and Time API

@glaforge #devoxx #groovylang Date / Time API 47 LocalDate.now(); today.with(TemporalAdjusters.lastDayOfMonth()).minusDays(2);
LocalDate.of(2012, Month.MAY, 14); dateOfBirth.plusYears(1); LocalDate date = LocalDate.of(2000, Month.NOVEMBER, 20); LocalDate nextWed = date.with(TemporalAdjusters.next(DayOfWeek.WEDNESDAY));

LocalDate.of(2012, Month.MAY, 14); dateOfBirth.plusYears(1); LocalDate date = LocalDate.of(2000, Month.NOVEMBER, 20); LocalDate nextWed = date.with(TemporalAdjusters.next(DayOfWeek.WEDNESDAY)); Groovy could add some operator overloading?

LocalDate.of(2012, Month.MAY, 14); dateOfBirth.plusYears(1); LocalDate date = LocalDate.of(2000, Month.NOVEMBER, 20); LocalDate nextWed = date.with(TemporalAdjusters.next(DayOfWeek.WEDNESDAY));

@glaforge #devoxx #groovylang Groovy’s date / time handling 48 import
static java.util.Calendar.* import groovy.time.* import org.codehaus.groovy.runtime.TimeCategory def cal = Calendar.instance cal.set(year: 2010, month: JULY, date: 9) assert FRIDAY == cal[DAY_OF_WEEK] use (TimeCategory) { 2.years + 3.months + 15.days + 23.minutes + 2.seconds 1.week - 1.day new Date() + 6.days 3.days.ago new Date() - 3 }

static java.util.Calendar.* import groovy.time.* import org.codehaus.groovy.runtime.TimeCategory def cal = Calendar.instance cal.set(year: 2010, month: JULY, date: 9) assert FRIDAY == cal[DAY_OF_WEEK] use (TimeCategory) { 2.years + 3.months + 15.days + 23.minutes + 2.seconds 1.week - 1.day new Date() + 6.days 3.days.ago new Date() - 3 } Groovy could provide the same for Date / Time

static java.util.Calendar.* import groovy.time.* import org.codehaus.groovy.runtime.TimeCategory def cal = Calendar.instance cal.set(year: 2010, month: JULY, date: 9) assert FRIDAY == cal[DAY_OF_WEEK] use (TimeCategory) { 2.years + 3.months + 15.days + 23.minutes + 2.seconds 1.week - 1.day new Date() + 6.days 3.days.ago new Date() - 3 }

Stream API

map map map map map reduce reduce reduce reduce reduce

Map / filter / reduce explained to your 6 year old

@glaforge #devoxx #groovylang Stream 51 persons.stream() .filter( p -> p.getAge()
< 18 ) .map( p -> p.getName().toUpperCase() ) .sorted() .collect(Collectors.joining(", "));

@glaforge #devoxx #groovylang Groovy’s functional style with GDK methods 52
persons .findAll { it.getAge() < 18 } .collect { it.name.toUpperCase() } .sort() .join(", ")

@glaforge #devoxx #groovylang Groovy using streams too! 53 persons.stream() .filter
{ it.age < 18 } .map { it.name.toUpperCase() } .sorted() .collect(Collectors.joining(", "))

{ it.age < 18 } .map { it.name.toUpperCase() } .sorted() .collect(Collectors.joining(", ")) Leveraging closure to « SAM » type coercion

{ it.age < 18 } .map { it.name.toUpperCase() } .sorted() .collect(Collectors.joining(", "))

@glaforge #devoxx #groovylang Optional 54 Optional<String> maybeName = Optional.of("Guillaume"); String
result = maybeName.orElse("unknown") if (maybeName.ifPresent()) { System.out.println(maybeName.get()); } else { System.out.println("unknown"); }

result = maybeName.orElse("unknown") if (maybeName.ifPresent()) { System.out.println(maybeName.get()); } else { System.out.println("unknown"); } Wrap something that can be potentially null

result = maybeName.orElse("unknown") if (maybeName.ifPresent()) { System.out.println(maybeName.get()); } else { System.out.println("unknown"); } Force handling the null value

You know you can customize the truth in Groovy?

You know you can customize the truth in Groovy? Just
implement a custom asBoolean() method!

@glaforge #devoxx #groovylang The law of Groovy Truth 56

@glaforge #devoxx #groovylang The law of Groovy Truth 56 Everything
that’s null, empty, zero-sized, equal to zero is false

@glaforge #devoxx #groovylang The law of Groovy Truth 56 Everything
that’s null, empty, zero-sized, equal to zero is false Otherwise, it’s true!

@glaforge #devoxx #groovylang Groovy truth, null handling, Elvis & Optional
58 def maybeName = Optional.of("Guillaume") def result = maybeName ?: "unknown" if (maybeName) { println maybeName.get() } else { println "unknown" } maybeName?.toUpperCase()

58 def maybeName = Optional.of("Guillaume") def result = maybeName ?: "unknown" if (maybeName) { println maybeName.get() } else { println "unknown" } maybeName?.toUpperCase() Elvis!

58 def maybeName = Optional.of("Guillaume") def result = maybeName ?: "unknown" if (maybeName) { println maybeName.get() } else { println "unknown" } maybeName?.toUpperCase() Groovy Truth!

58 def maybeName = Optional.of("Guillaume") def result = maybeName ?: "unknown" if (maybeName) { println maybeName.get() } else { println "unknown" } maybeName?.toUpperCase() Safe navigation

58 def maybeName = Optional.of("Guillaume") def result = maybeName ?: "unknown" if (maybeName) { println maybeName.get() } else { println "unknown" } maybeName?.toUpperCase() Interesting discussions on the mailing-list to further enhance usage of Optional from Groovy

58 def maybeName = Optional.of("Guillaume") def result = maybeName ?: "unknown" if (maybeName) { println maybeName.get() } else { println "unknown" } maybeName?.toUpperCase() Not Yet Implemented

58 def maybeName = Optional.of("Guillaume") def result = maybeName ?: "unknown" if (maybeName) { println maybeName.get() } else { println "unknown" } maybeName?.toUpperCase()

Nashorn

Nashorn Speak German?

@glaforge #devoxx #groovylang Call JavaScript from Groovy with JSR-223 60
def manager = new ScriptEngineManager() def engine = manager.getEngineByName("nashorn") assert engine.eval("{} + []") == 0

@glaforge #devoxx #groovylang Call JavaScript from Groovy with JSR-223 60
def manager = new ScriptEngineManager() def engine = manager.getEngineByName("nashorn") assert engine.eval("{} + []") == 0 Sane JavaScript logic :-)

@glaforge #devoxx #groovylang GrooScript — http://grooscript.org/ 61 JS

@glaforge #devoxx #groovylang GrooScript — http://grooscript.org/ 61 JS Gradle &
Grails plugins available Examples available with Ratpack, Node.JS…

Turtles all the way down!

Turtles all the way down! Full Groovy!

Turtles all the way down! Full Groovy! Back to front

Turtles all the way down! Full Groovy! Back to front
Front to back

JavaFx… …the new Swing

@glaforge #devoxx #groovylang GroovyFX 64 import javafx.scene.Scene import static groovyx.javafx.GroovyFX.start
def chamber = ["5 Stelle": 108, "Italia.\nBene commune": 340, "Con Monti per l'Italia": 45, "Berlusconi": 124, "others": 4] start { stage(title: 'Italian chamber of Deputies', width: 1024, height: 700, visible: true) { Scene s = scene { tilePane { barChart(barGap: 10, categoryGap: 20, title: "Italy's election in February 2013") { series(name: 'Chamber (seats)', data: ['5 Stelle', 17.5, 'Monti', 7.8, 'Bene commune', 55, 'Berlusconi', 19.9]) series(name: 'Senate (seats)', data: ['5 Stelle', 17.4, 'Monti', 6.1, 'Bene commune', 39.1, 'Berlusconi', 37.1]) } pieChart(data: chamber, title: "Chamber of Deputies") } } s.stylesheets.add("Chart.css") } }

@glaforge #devoxx #groovylang GroovyFX 64 import javafx.scene.Scene import static groovyx.javafx.GroovyFX.start
def chamber = ["5 Stelle": 108, "Italia.\nBene commune": 340, "Con Monti per l'Italia": 45, "Berlusconi": 124, "others": 4] start { stage(title: 'Italian chamber of Deputies', width: 1024, height: 700, visible: true) { Scene s = scene { tilePane { barChart(barGap: 10, categoryGap: 20, title: "Italy's election in February 2013") { series(name: 'Chamber (seats)', data: ['5 Stelle', 17.5, 'Monti', 7.8, 'Bene commune', 55, 'Berlusconi', 19.9]) series(name: 'Senate (seats)', data: ['5 Stelle', 17.4, 'Monti', 6.1, 'Bene commune', 39.1, 'Berlusconi', 37.1]) } pieChart(data: chamber, title: "Chamber of Deputies") } } s.stylesheets.add("Chart.css") } } Groovy builder to the rescue!

@glaforge #devoxx #groovylang Beyond Java

@glaforge #devoxx #groovylang Android

@glaforge #devoxx #groovylang Android support • You can use Groovy
to code Android apps! • use Groovy 2.4.0-beta-1+ • prefer @CompileStatic • Two great posts to get started: • http://melix.github.io/blog/2014/06/grooid.html • http://melix.github.io/blog/2014/06/grooid2.html 67

@glaforge #devoxx #groovylang New York Times — Getting Groovy with
68

@glaforge #devoxx #groovylang New York Times — Getting Groovy with
68 http://bit.ly/nyt-groovy

@glaforge #devoxx #groovylang What does NYT likes about Groovy on
Android? • No Java 8, no lambda on Android… 69 Func0 func = new Func0<string>() { @Override public String call() { return "my content"; } }; Async.start(func);

Android? • No Java 8, no lambda on Android… 70 Async.start { "my content" }

Android? • No Java 8, no lambda on Android… 70 Async.start { "my content" } Good bye annonymous inner classes!

Android? • Groovy code more concise and more readable • but just as type-safe as needed!  (with @TypeChecked) • but just as fast as needed!  (with @CompileStatic) 71

@glaforge #devoxx #groovylang Android support 72

@glaforge #devoxx #groovylang Android support 72 Source code available: https://github.com/melix/gr8confagenda

@glaforge #devoxx #groovylang A rich Groovy ecosystem

@glaforge #devoxx #groovylang Grails — web framework 74 @Grab("com.h2database:h2:1.3.173") import
grails.persistence.* @Entity @Resource(uri='/books') class Book { String title }

@glaforge #devoxx #groovylang Grails — web framework 74 @Grab("com.h2database:h2:1.3.173") import
grails.persistence.* @Entity @Resource(uri='/books') class Book { String title } One class, one command, and you’ve got a full REST CRUD application!

@glaforge #devoxx #groovylang Ratpack — web framework 75 @GrabResolver("https://oss.jfrog.org/artifactory/repo") @Grab("org.ratpack-framework:ratpack-groovy:0.9.8")
import static org.ratpackframework.groovy.RatpackScript.ratpack import static org.ratpackframework.groovy.Template.groovyTemplate ratpack { handlers { get { response.send "Welcome!" } get("date") { render groovyTemplate("date.html") } assets "public" } }

@glaforge #devoxx #groovylang Ratpack — web framework 75 @GrabResolver("https://oss.jfrog.org/artifactory/repo") @Grab("org.ratpack-framework:ratpack-groovy:0.9.8")
import static org.ratpackframework.groovy.RatpackScript.ratpack import static org.ratpackframework.groovy.Template.groovyTemplate ratpack { handlers { get { response.send "Welcome!" } get("date") { render groovyTemplate("date.html") } assets "public" } } Lightweight Netty-based web application toolkit

@glaforge #devoxx #groovylang @ArtifactProviderFor(GriffonModel) class ConsoleModel { String scriptSource @Observable
Object scriptResult @Observable boolean enabled = true } Griffon — rich desktop applications 76

Object scriptResult @Observable boolean enabled = true } Griffon — rich desktop applications 76 Model

Object scriptResult @Observable boolean enabled = true } Griffon — rich desktop applications 76 Model @ArtifactProviderFor(GriffonController) class ConsoleController { def model @Inject Evaluator evaluator void executeScript() { model.enabled = false def result try { result = evaluator.evaluate(model.scriptSource) } finally { model.enabled = true model.scriptResult = result } } } Controller

Object scriptResult @Observable boolean enabled = true } Griffon — rich desktop applications 76 Model @ArtifactProviderFor(GriffonController) class ConsoleController { def model @Inject Evaluator evaluator void executeScript() { model.enabled = false def result try { result = evaluator.evaluate(model.scriptSource) } finally { model.enabled = true model.scriptResult = result } } } Controller application(title: application.configuration['application.title'], pack: true, locationByPlatform: true, id: 'mainWindow', iconImage: imageIcon('/griffon-icon-48x48.png').image, iconImages: [imageIcon('/griffon-icon-48x48.png').image, imageIcon('/griffon-icon-32x32.png').image, imageIcon('/griffon-icon-16x16.png').image]) { panel(border: emptyBorder(6)) { borderLayout() scrollPane(constraints: CENTER) { textArea(text: bind(target: model, 'scriptSource'), enabled: bind { model.enabled }, columns: 40, rows: 10) } hbox(constraints: SOUTH) { button(executeScriptAction) hstrut(5) label('Result:') hstrut(5) textField(editable: false, text: bind { model.scriptResult }) } } } View

@glaforge #devoxx #groovylang Spock — unit testing & specification 77
@Grab('org.spockframework:spock-core:0.7-groovy-2.0') import spock.lang.* class MathSpec extends Specification { def "maximum of two numbers"() { expect: Math.max(a, b) == c where: a | b || c 1 | 3 || 3 7 | 4 || 7 0 | 0 || 0 } }

@Grab('org.spockframework:spock-core:0.7-groovy-2.0') import spock.lang.* class MathSpec extends Specification { def "maximum of two numbers"() { expect: Math.max(a, b) == c where: a | b || c 1 | 3 || 3 7 | 4 || 7 0 | 0 || 0 } } Readable & concise expectations

@Grab('org.spockframework:spock-core:0.7-groovy-2.0') import spock.lang.* class MathSpec extends Specification { def "maximum of two numbers"() { expect: Math.max(a, b) == c where: a | b || c 1 | 3 || 3 7 | 4 || 7 0 | 0 || 0 } } Readable & concise expectations Awesome data-driven tests with a wiki-like notation

@glaforge #devoxx #groovylang Geb — browser automation 78 import geb.Browser
Browser.drive { go "http://myapp.com/login" assert $("h1").text() == "Please Login" $("form.login").with { username = "admin" password = "password" login().click() } assert $("h1").text() ==   "Admin Section" }

Browser.drive { go "http://myapp.com/login" assert $("h1").text() == "Please Login" $("form.login").with { username = "admin" password = "password" login().click() } assert $("h1").text() ==   "Admin Section" } Drive your browser

Browser.drive { go "http://myapp.com/login" assert $("h1").text() == "Please Login" $("form.login").with { username = "admin" password = "password" login().click() } assert $("h1").text() ==   "Admin Section" } Drive your browser JQuery-like selectors

Browser.drive { go "http://myapp.com/login" assert $("h1").text() == "Please Login" $("form.login").with { username = "admin" password = "password" login().click() } assert $("h1").text() ==   "Admin Section" } Drive your browser JQuery-like selectors Fill & submit forms

@glaforge #devoxx #groovylang Gradle — build automation 79 apply plugin:
'java' apply plugin: 'eclipse' sourceCompatibility = 1.5 version = '1.0' jar { manifest { attributes 'Implementation-Title': 'Gradle Quickstart' } } repositories { mavenCentral() } dependencies { compile ‘commons-collections:commons-collections:3.2’ testCompile 'junit:junit:4.+' } uploadArchives { repositories { flatDir { dirs 'repos' } } }

@glaforge #devoxx #groovylang Gradle — build automation 79 apply plugin:
'java' apply plugin: 'eclipse' sourceCompatibility = 1.5 version = '1.0' jar { manifest { attributes 'Implementation-Title': 'Gradle Quickstart' } } repositories { mavenCentral() } dependencies { compile ‘commons-collections:commons-collections:3.2’ testCompile 'junit:junit:4.+' } uploadArchives { repositories { flatDir { dirs 'repos' } } } Powerful and readable DSL for automating your builds and deployments

@glaforge #devoxx #groovylang GPars: concurrency / parallelism / async /
… 80 import static groovyx.gpars.actor.Actors.actor def decryptor = actor { loop { react { message -> if (message instanceof String) reply message.reverse() else stop() } } } def console = actor { decryptor.send 'lellarap si yvoorG' react { println 'Decrypted message: ${it}' decryptor.send false } } [decryptor, console]*.join()

… 80 import static groovyx.gpars.actor.Actors.actor def decryptor = actor { loop { react { message -> if (message instanceof String) reply message.reverse() else stop() } } } def console = actor { decryptor.send 'lellarap si yvoorG' react { println 'Decrypted message: ${it}' decryptor.send false } } [decryptor, console]*.join() Actors…

… 80 import static groovyx.gpars.actor.Actors.actor def decryptor = actor { loop { react { message -> if (message instanceof String) reply message.reverse() else stop() } } } def console = actor { decryptor.send 'lellarap si yvoorG' react { println 'Decrypted message: ${it}' decryptor.send false } } [decryptor, console]*.join() Actors… But also: Dataflow concurrency, CSP, agents, concurrent collection processing, fork / join, composable async functions, STM

@glaforge #devoxx #groovylang Groovy modules

@glaforge #devoxx #groovylang Groovy modules • Ant scripting • JMX
• JSON • Servlet • Swing • SQL • Templating • Testing • XML 82

@glaforge #devoxx #groovylang Groovy modules • Ant scripting • JMX
• JSON • Servlet • Swing • SQL • Templating • Testing • XML 83

@glaforge #devoxx #groovylang Ant + XML 84 def writer =
new StringWriter() def mkp = new MarkupBuilder(writer) mkp.html { head { title 'Build notification' } body { p 'Your build was successful' } } new AntBuilder().mail(mailhost: 'localhost', messagemimetype: 'text/html', subject: 'Build successful') { from address: '[email protected]' to address: '[email protected]' message writer attchments { fileset(dir: 'dist') { include name: '**/logs*.txt' } } }

new StringWriter() def mkp = new MarkupBuilder(writer) mkp.html { head { title 'Build notification' } body { p 'Your build was successful' } } new AntBuilder().mail(mailhost: 'localhost', messagemimetype: 'text/html', subject: 'Build successful') { from address: '[email protected]' to address: '[email protected]' message writer attchments { fileset(dir: 'dist') { include name: '**/logs*.txt' } } } Generate some HTML with the XML support

new StringWriter() def mkp = new MarkupBuilder(writer) mkp.html { head { title 'Build notification' } body { p 'Your build was successful' } } new AntBuilder().mail(mailhost: 'localhost', messagemimetype: 'text/html', subject: 'Build successful') { from address: '[email protected]' to address: '[email protected]' message writer attchments { fileset(dir: 'dist') { include name: '**/logs*.txt' } } } Generate some HTML with the XML support Use the Ant builder and the mail task

new StringWriter() def mkp = new MarkupBuilder(writer) mkp.html { head { title 'Build notification' } body { p 'Your build was successful' } } new AntBuilder().mail(mailhost: 'localhost', messagemimetype: 'text/html', subject: 'Build successful') { from address: '[email protected]' to address: '[email protected]' message writer attchments { fileset(dir: 'dist') { include name: '**/logs*.txt' } } } Generate some HTML with the XML support Use the Ant builder and the mail task Use the Ant’s fileset

@glaforge #devoxx #groovylang JSON support — creating JSON 85 import
groovy.json.* def json = new JsonBuilder() json.person { name 'Guillaume' age 37 daughters 'Marion', 'Erine' address { street '1 Main Street' zip 75001 city 'Paris' } }

@glaforge #devoxx #groovylang JSON support — creating JSON 85 import
groovy.json.* def json = new JsonBuilder() json.person { name 'Guillaume' age 37 daughters 'Marion', 'Erine' address { street '1 Main Street' zip 75001 city 'Paris' } } { "person": { "name": "Guillaume", "age": 37, "daughters": [ "Marion", "Erine" ], "address": { "street": "1 Main Street", "zip": 75001, "city": "Paris" } } }

@glaforge #devoxx #groovylang JSON support — parsing JSON 86 import
groovy.json.* def url =   "https://api.github.com/repos/groovy/groovy-core/commits" def commits = new JsonSlurper().parseText(url.toURL().text) assert commits[0].commit.author.name == 'Cedric Champeau'

@glaforge #devoxx #groovylang JSON support — parsing JSON 86 import
groovy.json.* def url =   "https://api.github.com/repos/groovy/groovy-core/commits" def commits = new JsonSlurper().parseText(url.toURL().text) assert commits[0].commit.author.name == 'Cedric Champeau' The power of a dynamic language!

@glaforge #devoxx #groovylang New markup template engine • Based on
the principles of Groovy’s « builders » • and particularly the MarkupBuilder class  for generating arbitrary XML / HTML payloads • Compiled statically for fast template rendering • Internationalization aware • provide the desired Locale in the conﬁguration object • usual sufﬁx notation template_fr_FR.tpl 87

@glaforge #devoxx #groovylang New markup template engine • Based on
the principles of Groovy’s « builders » • and particularly the MarkupBuilder class  for generating arbitrary XML / HTML payloads • Compiled statically for fast template rendering • Internationalization aware • provide the desired Locale in the conﬁguration object • usual sufﬁx notation template_fr_FR.tpl 87 Spring Boot approved

@glaforge #devoxx #groovylang Markup template engine — the idea 88
cars { cars.each { car(make: it.make, name: it.name) } }

cars { cars.each { car(make: it.make, name: it.name) } } Your template

cars { cars.each { car(make: it.make, name: it.name) } } model = [cars: [ new Car(make: 'Peugeot', name: '508'), new Car(make: 'Toyota', name: 'Prius’) ]]

cars { cars.each { car(make: it.make, name: it.name) } } model = [cars: [ new Car(make: 'Peugeot', name: '508'), new Car(make: 'Toyota', name: 'Prius’) ]] Feed a model into your template

cars { cars.each { car(make: it.make, name: it.name) } } model = [cars: [ new Car(make: 'Peugeot', name: '508'), new Car(make: 'Toyota', name: 'Prius’) ]] <cars> <car make='Peugeot' name='508'/> <car make='Toyota' name='Prius'/> </cars>

cars { cars.each { car(make: it.make, name: it.name) } } model = [cars: [ new Car(make: 'Peugeot', name: '508'), new Car(make: 'Toyota', name: 'Prius’) ]] <cars> <car make='Peugeot' name='508'/> <car make='Toyota' name='Prius'/> </cars> Generate the XML output

cars { cars.each { car(make: it.make, name: it.name) } } model = [cars: [ new Car(make: 'Peugeot', name: '508'), new Car(make: 'Toyota', name: 'Prius’) ]] <cars> <car make='Peugeot' name='508'/> <car make='Toyota' name='Prius'/> </cars>

@glaforge #devoxx #groovylang Markup template engine — in action 89
import groovy.text.markup.* def config = new TemplateConfiguration() def engine = new MarkupTemplateEngine(config) def tmpl = engine.createTemplate(''' p("Hello ${model.name}") ''') def model = [name: 'World'] System.out << tmpl.make(model)

@glaforge #devoxx #groovylang Summary

@glaforge #devoxx #groovylang Back to our original question… Do we
still need Groovy now that we have Java 8? 91

@glaforge #devoxx #groovylang Longer answer: Yes, because… • You can
beneﬁt from Java 8 in Groovy 93 Synergy  the whole is   greater than the sum of the parts

@glaforge #devoxx #groovylang Longer answer: Yes, because… • Groovy goes
beyond what Java 8 offers 94 Beyond  Groovy always tries to add something to the table

@glaforge #devoxx #groovylang Questions still open: Syntax support for… •
lambdas: not necessarily (confusing / duplication) • method references • enhance method closures or replace them with method references • interface default methods • yes: traits methods aren’t default methods • repeating annotations • yes: not urgent, but less boilerplate is good • annotations on type: yes, opens up new possibilities for targets of local AST transformation • interface static methods yes: for Java compatibility 95

@glaforge #devoxx #groovylang Further possible API enhancements • Make Optional
Groovy-friendly • with regards to Groovy Truth • accessing the wrapped value • More Groovy methods for… • NIO • Streams • Date / time • Operator overloading for Date / time • for arithmetics on instants and durations 96

@glaforge #devoxx #groovylang Further possible API enhancements • Make Optional
Groovy-friendly • with regards to Groovy Truth • accessing the wrapped value • More Groovy methods for… • NIO • Streams • Date / time • Operator overloading for Date / time • for arithmetics on instants and durations 96 Community feedback & contributions welcome!

@glaforge #devoxx #groovylang Q & A

@glaforge #devoxx #groovylang Image credits • Antwerp • http://www.visitﬂanders.in/binaries/IMG_7895.jpg, http://www.semindex.be/upload/SemIndex/images/Accommodation/23/4_zaal6_original.jpg
• Antwerp central station • http://4.bp.blogspot.com/_4dEsCVlFCgA/S7horBAdM5I/AAAAAAAAALU/eXOhxk2ou-8/s1600/Antwerp+Station.jpg • Question mark •http://www.mynamesnotmommy.com/wp-content/uploads/2013/05/question-mark.png • Get out! •http://static.comicvine.com/uploads/original/11/117995/3772037-0075368930-27616.jpg • Yes •http://soloprpro.com/wp-content/uploads/2013/08/yes.jpg • Brain • http://www.semel.ucla.edu/sites/all/ﬁles/users/user-412/dreamstime_xxl_17754591%20(2).jpg • Many thanks • http://www.trys.ie/wp-content/uploads/2013/06/many-thanks.jpg • Swing • http://makemesomethingspecial.co.uk/wp-content/uploads/2012/10/Solid-Oak-Handmade-Spliced-Swing-With-Personalised-Engraving-10867.jpg 99

@glaforge #devoxx #groovylang Image credits • Synergy •http://www.wildblueberries.com/wp-content/uploads/blogger/_YhH8fDK5-kU/S_5kYWwgAbI/AAAAAAAAAKU/JQ_-ISfT9KY/s1600/ teamwork.jpg •
Buzz Lightyear •http://www.disneypictures.net/data/media/202/Buzz_Lightyear_hd.jpg • Start wars spaceship •http://swc.fs2downloads.com/media/screenshots/Support_Trans/Shuttle/lambda003.jpg • Lambda character •http://lambda.ninjackaton.ninja-squad.com/images/lambda.png • Man clock •http://3.bp.blogspot.com/-7hLQ9tnmA84/TuTIoLRLMTI/AAAAAAAABWM/g7ahyLCRjJQ/s1600/Harold+Lloyd+Safety+Last.jpg • Stream •http://wallpaperswide.com/forest_stream-wallpapers.html • Nashorn (rhino) •http://2010sdafrika.ﬁles.wordpress.com/2012/07/hi_257587-nashorn-c-naturepl-com-mark-carwardine-wwf-canon.jpg 100

@glaforge #devoxx #groovylang Image credits • Disclaimer • http://3.bp.blogspot.com/-RGnBpjXTCQA/Tj2h_JsLigI/AAAAAAAABbg/AB5ZZYzuE5w/s1600/disclaimer.jpg •
Hammer / justice / truth • http://www.bombayrealty.in/images/disclaimer.jpg • Law • http://www.permanentmakeupbymv.com/wp-content/uploads/2014/07/law-2.jpg • Glasses / readable • http://a.fastcompany.net/multisite_ﬁles/coexist/imagecache/1280/poster/2013/02/1681393-poster-1280-responsive-eye-chart.jpg • We need you • http://www.bostonbreakerssoccer.com/imgs/ABOUT/volopps/we%20need%20you.JPG • Golden Gate • http://www.airpano.com/ﬁles/San-Francisco-Golden-Gate-USA/sf_golden_gate.jpg • Turtles • http://33.media.tumblr.com/77095e3a37acb2272133c405b1f7ba54/tumblr_myfydjNgXJ1s20kxvo1_1280.jpg • Annotations • http://3.bp.blogspot.com/-f94n9BHko_s/T35ELs7nYvI/AAAAAAAAAKg/qe06LRPH9U4/s1600/IMG_1721.JPG 101

@glaforge #devoxx #groovylang Image credits • Builders • http://detroittraining.com/wp-content/uploads/Construction-Women2.jpg •
Sandwich ingredients • http://www.fromages-de-terroirs.com/IMG/MEULE_DETOUREE_72_DPI_-2.jpg • http://eboutique-hebergement.orange-business.com/WebRoot/Orange/Shops/Madeinalsace/4B02/6320/943E/DB4F/DDBF/0A0A/33E8/4BC8/ iStock_000008775559XSmall.jpg • http://www.cmonprimeur.fr/images/25834-vegetable-pictures%5B1%5D.jpg • http://1.bp.blogspot.com/-27UoqYeYtY4/T4PAr4zGSnI/AAAAAAAAA3s/lleE-NOh0LE/s1600/IMG_1528.JPG • http://www.growingpatch.com/wp-content/uploads/2014/05/tomato-9.jpg • http://vitaminsandhealthsupplements.com/wp-content/uploads/2013/08/fresh-sliced-tomato.jpg • http://2.bp.blogspot.com/-3pPmRhBHv9s/T3D-EtLlN1I/AAAAAAAAAgg/Y5oTM84nGb8/s1600/cochon+2.jpg • http://www.salamarket.fr/wp-content/uploads/steak-hach%C3%A9.jpg • http://www.quinzanisbakery.com/images/bread-vienna.jpg • http://www.saucissonvaudois.qc.ca/images/produits/Jambon_blanc.jpg • http://www.audion.com/system/public/categories/125/images/bread-sandwich.jpg 102

Groovy in the light of Java 8 -- Devoxx 2014

Groovy in the light of Java 8 -- Devoxx 2014

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