Given Groovy Who Needs Java

Given Groovy Who Needs Java?

Prof Russel Winder
http://www.russel.org.uk

email: russel@winder.org.uk
xmpp: russel@winder.org.uk
twitter: @russel_winder

Copyright © 2012 Russel Winder 1

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Introduction


Groovy was…
● …designed to be a dynamic symbiote to Java.

● Java is statically typed.
● Groovy is optionally typed.


Groovy was…
● …designed to have a very lightweight syntax.

● Literal syntax for lists and maps.
● As little punctuation as possible.


Groovy was…
● …designed to work with code as first class entity.

● Closures and functional approach from the outset.
● No waiting for Java 8.


Code


println 'Hello World.'


public class testAll_GroovyTestCase extends GroovyTestCase {
void test_helloWorld_trivial() {
assert 'helloWorld_trivial.groovy'.execute().text == 'Hello World.n'
}
}

Power asserts

JUnit3 behind the scenes


@Grab('org.spockframework:spock:0.7-groovy2.0')
import spock.lang.Specification

class TestAll_Spock extends Specification {
def "ensure the hello world program prints hello world"() {
expect:
'helloWorld_trivial.groovy'.execute().text == 'Hello World.n'
}
}


def datum = ['Hello', ' ', 'World', '.'].join('')

println datum


String datum = ['Hello', ' ', 'World', '.'].join('')

println datum


datum = ['Hello', ' ', 'World', '.'].join('')

println datum


words = [:]

words.third = 'World'
words << [first: 'Hello', fourth: '.']
words['second'] = ' '

sequence = ['first', 'second', 'third', 'fourth']

println(sequence.collect{words[it]}.join(''))

@GrabResolver(name='atlassian',
root='https://maven.atlassian.com/content/groups/public/')
@Grab('org.swift.tools:gint:1.5.0')
import org.swift.tools.Gint

includeTool << Gint

gint.initialize(this)

new File('.').eachFileMatch(~/helloWorld_.*.groovy/) {
gint.add(name: it.name, inline: { it.name.execute().text == 'Hello World.n' })
}

gint.finalizeTest()

import groovy.xml.MarkupBuilder

new MarkupBuilder().html{
head{
title 'Hello World.'
}
body{
(0 ..< 3).each {
em('Hello')
}
}
}

<html>
 <head>
 <title>Hello World.</title>
 </head>
 <body>
 Hello
 Hello
 Hello
 </body>
</html>

html = new XmlParser().parse(System.in)
assert html.head.title.text() == 'Hello World.'
assert html.body.em.text() == 'HelloHelloHello'


import javax.swing.WindowConstants

import groovy.swing.SwingBuilder

def widget = new SwingBuilder().frame(
title: 'Hello World Window',
size: [200, 100],
defaultCloseOperation: WindowConstants.EXIT_ON_CLOSE
){
panel {
button(text:'Say Hello', actionPerformed: { println 'Hello.' })
}
}
widget.show()


final n = 100000
final delta = 1.0 / n
final startTime = System.nanoTime()
def sum = 0.0
for (i in 1 .. n) { sum += 1 / (1 + ((i - 0.5) * delta) ** 2) }
final pi = 4 * delta * sum
final elapseTime = (System.nanoTime() - startTime) / 1e9
Output.out(getClass().name, pi, n, elapseTime)


final int n = 1000000000
final double delta = 1.0 / n
final startTimeNanos = System.nanoTime()
double sum = 0.0
for (int i = 1; i <= n; ++i) {
final double x = (i - 0.5d) * delta
sum += 1.0d / (1.0d + x * x)
}
final double pi = 4.0 * delta * sum
final elapseTime = (System.nanoTime() - startTimeNanos) / 1e9

import groovy.transform.CompileStatic

@CompileStatic execute() {
final int n = 1000000000
final startTimeNanos = System.nanoTime ()
double sum = 0.0
for (int i = 1; i <= n; ++i) {
sum += 1.0d / (1.0d + x * x)
}
final double pi = 4.0 * delta * sum
}

execute()

final int n = 10000000
final double pi = 4.0 * delta * (1i .. n).sum {int i ->
1.0d / (1.0d + x * x)
}


import groovy.transform.CompileStatic

@CompileStatic execute() {
final int n = 10000000
final double pi = 4.0 * delta * (double)((1i .. n).sum {int i ->
1.0d / (1.0d + x * x)
})
}

execute()


import groovyx.gpars.ParallelEnhancer

void execute(final numberOfTasks) {
final n = 1000000000
final delta = 1.0 / n
final startTimeNanos = System.nanoTime ()
final sliceSize = (int)(n / numberOfTasks)
final items = 0 ..< numberOfTasks
ParallelEnhancer.enhanceInstance(items)
final pi = 4.0 * delta * items.collectParallel {taskId ->
PartialSum.dynamicCompile(taskId, sliceSize, delta)
}.sumParallel()
Output.out(getClass().name, pi, n, elapseTime, numberOfTasks)
}

execute 1
execute 2
execute 8
execute 32

static double dynamicCompile(final int taskId, final int sliceSize, final double delta) {
final int start = 1i + taskId * sliceSize
final int end = (taskId + 1i) * sliceSize
double sum = 0.0d
for (int i = start; i <= end; ++i) {
sum += 1.0d / (1.0d + x * x)
}
sum
}

Conclusion


There is nothing that Java can do

that Groovy cannot do better.


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Prof Russel Winder



Challenge


Problem

Groovy
Java

Develop faster
Execute faster
Can be done at all



Prof Russel Winder



Given Groovy Who Needs Java

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