Given Groovy Who Needs Java

Copyright © 2012 Russel Winder 1

Given Groovy Who Needs Java?

Prof Russel Winder

http://www.russel.org.uk

email: [email protected]: [email protected]

twitter: @russel_winder

mailto:[email protected]


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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 = 100000final delta = 1.0 / nfinal startTime = System.nanoTime()def sum = 0.0for (i in 1 .. n) { sum += 1 / (1 + ((i - 0.5) * delta) ** 2) }final pi = 4 * delta * sumfinal elapseTime = (System.nanoTime() - startTime) / 1e9Output.out(getClass().name, pi, n, elapseTime)


final int n = 1000000000final double delta = 1.0 / nfinal startTimeNanos = System.nanoTime()double sum = 0.0for (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 * sumfinal elapseTime = (System.nanoTime() - startTimeNanos) / 1e9Output.out(getClass().name, pi, n, elapseTime)


import groovy.transform.CompileStatic

@CompileStatic execute() { 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 Output.out(getClass().name, pi, n, elapseTime)}

execute()


final int n = 10000000final double delta = 1.0 / nfinal startTime = System.nanoTime()final double pi = 4.0 * delta * (1i .. n).sum {int i -> final double x = (i - 0.5d) * delta 1.0d / (1.0d + x * x)}final elapseTime = (System.nanoTime() - startTime) / 1e9Output.out(getClass().name, pi, n, elapseTime)


import groovy.transform.CompileStatic

@CompileStatic execute() { final int n = 10000000 final double delta = 1.0 / n final startTime = System.nanoTime() final double pi = 4.0 * delta * (double)((1i .. n).sum {int i -> final double x = (i - 0.5d) * delta 1.0d / (1.0d + x * x) }) final elapseTime = (System.nanoTime() - startTime) / 1e9 Output.out(getClass().name, pi, n, elapseTime)}

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() final elapseTime = (System.nanoTime() - startTimeNanos) / 1e9 Output.out(getClass().name, pi, n, elapseTime, numberOfTasks)}

execute 1execute 2execute 8execute 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) { final double x = (i - 0.5d) * delta 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

GroovyJava

Develop fasterExecute fasterCan be done at all



Prof Russel Winder

Technology

Given Groovy Who Needs Java