Groovy 1.7 and 1.8 Progress

State
jeudi 16 décembre 2010
of the Union

Guillaume Laforge / @glaforge

• Groovy Project Manager
• Head of Groovy Development
at SpringSource
• Initiator of the Grails framework
• Founder of the Gaelyk toolkit
• Co-author of Groovy in Action
• Member of «Les Cast Codeurs» podcast

• Speaker: JavaOne, QCon, JavaZone, Sun TechDays,
Devoxx, The Spring Experience, SpringOne2GX,
JAX, Dynamic Language World, IJTC, and more...

Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited. 2

Agenda

•Past
– Groovy 1.6 flashback

•Present
– Groovy 1.7 novelties
– A few Groovy 1.7.x refinements

•Future
– What’s cooking for 1.8 and beyond


But first... some figures...
Downloads Moving Average (year)
Groovy downloads per month
200000

150000

100000

50000

0
déc.-07 févr.-08 avr.-08 juin-08 août-08 oct.-08 janv.-09 mars-09 mai-09 juil.-09 sept.-09 nov.-09 janv.-10 mars-10 mai-10 juil.-10


200000

150000

100000

50000

Groovy 1.5

0


200000

150000

100000

G2One
acquisition
50000

Groovy 1.5

0


200000

Groovy 1.6

150000

100000

G2One
acquisition
50000

Groovy 1.5

0


200000 Groovy 1.7

Groovy 1.6

150000

100000

G2One
acquisition
50000

Groovy 1.5

0


200000 Groovy 1.7

Groovy 1.6

8 5 K
150000

100000

50000

Groovy 1.5
1 G2One
acquisition

0


Groovy 1.7.6 and 1.8-beta-3


looking into the Past

Big highlights of Groovy 1.6

• Greater compile-time and runtime performance
• Multiple assignments
• Optional return for if/else and try/catch/finally
• Java 5 annotation definition
• AST Transformations
• The Grape module and dependency system
• Various Swing related improvements
• JMX Builder
• Metaprogramming additions
• JSR-223 scripting engine built-in
• Out-of-the-box OSGi support


• Greater compile-time and runtime performance
• Multiple assignments
• Optional return for if/else and try/catch/finally
• Java 5 annotation definition
• AST Transformations
• The Grape module and dependency system
• Various Swing related improvements
• JMX Builder
• Metaprogramming additions
• JSR-223 scripting engine built-in
• Out-of-the-box OSGi support

Multiple assignement

// multiple assignment
def (a, b) = [1, 2]
assert a == 1 && b == 2

// with typed variables
def (int c, String d) = [3, "Hi"]
assert c == 3 && d == "Hi"

def geocode(String place) { [48.8, 2.3] }
def lat, lng
// assignment to existing variables
(lat, lng) = geocode('Paris')

// classical variable swaping example
(a, b) = [b, a]


More optional return

// optional return for if statements
def m1() {
    if (true) 1
    else 0
}
assert m1() == 1

// optional return for try/catch/finally
def m2(bool) {
    try {
        if (bool) throw new Exception()
        1
    } catch (any) { 2 }
    finally { 3 }
}
assert m2(true) == 2 && m2(false) == 1


AST Transformation (1/2)

• Groovy 1.6 introduced AST Transformations
– AST: Abstract Syntax Tree
• Ability to change what’s being compiled by the
Groovy compiler... at compile time
–No runtime impact!
– Change the semantics of your programs! Even hijack the
Groovy syntax!
– Implementing recurring patterns in your code base
– Remove boiler-plate code
• Two kinds: global and local
– triggered by annotations


AST Transformations (2/2)

• Transformations introduced in 1.6
– @Singleton
– @Immutable, @Lazy, @Delegate
– @Newify
– @Category, @Mixin
– @PackageScope
– Swing’s @Bindable and @Vetoable
– Grape’s own @Grab


@Immutable

• To properly implement immutable classes
– No mutations — state musn’t change
– Private final fields
– Defensive copying of mutable components
– Proper equals() / hashCode() / toString()
for comparisons or as keys in maps

@Immutable class Coordinates {
Double lat, lng
}
def c1 = new Coordinates(lat: 48.8, lng: 2.5)
def c2 = new Coordinates(48.8, 2.5)
assert c1 == c2


Grab a grape!

• Simple distribution and sharing of Groovy scripts
• Dependencies stored locally
– Can even use your own local repositories

@Grab(group   = 'org.mortbay.jetty',
      module  = 'jetty‐embedded',
      version = '6.1.0')
def startServer() {
    def srv = new Server(8080)
SIONS)
    def ctx = new Context(srv , "/", SES
    ctx.resourceBase = "."
ovy")
     ctx.addServlet(GroovyServlet, "*.gro
    srv.start()
}


into the Present...


• Anonymous Inner Classes and Nested Classes
• Annotations anywhere
• Grape improvements
• Power Asserts
• AST Viewer
• AST Builder
• Customize the Groovy Truth!
• Rewrite of the GroovyScriptEngine
• Groovy Console improvements
• SQL support refinements



• Annotations anywhere
• Grape improvements
• Power Asserts
• AST Viewer
• AST Builder
• Customize the Groovy Truth!
• Rewrite of the GroovyScriptEngine
• Groovy Console improvements
• SQL support refinements


AIC and NC



AIC and NC


Fo rJ ava
’n p aste
c opy
atib ility
co mp
sak e :-)


Annonymous Inner Classes

bo olean called = false
Timer ti mer = new Timer()

timer.schedule(n ew TimerTask() {
    void run() {
         called = true
    }
}, 0)

sleep 100
assert called


Annonymous Inner Classes

bo olean called = false
Timer ti mer = new Timer()

timer.schedule(n ew TimerTask() {
    void run() {
         called = true
    }
{ called = true }
}, 0) as TimerTask

sleep 100
assert called


Nested Classes

class Environment {
    static class Production
         extends Environment {}
    static class Development
         extends Environment {}
}

new Environment.Production()


Anotations almost anywhere

• You can put annotations
– on imports
– on packages
– on variable declarations

• Examples with @Grab following...


Grape improvements (1/4)

• @Grab on import

@Grab(group = 'net.sf.json‐lib',
     module = 'json‐lib',
    version = '2.3',
classifier = 'jdk15')
import net.sf.json.groovy.*

assert new JsonSlurper().parseText(
new JsonGroovyBuilder().json {
    book(title: "Groovy in Action",
         author: "Dierk König et al")
}.toString ()).book.title == "Groovy in Action"



• Shorter module / artifact / version parameter
– Example of an annotation on a variable declaration

@Grab('net.sf.json‐lib:json‐lib:2.3:jdk15')
()
def builder = new net.sf.json.groovy.JsonGroovyBuilder

def books = builder.books {
    book(title: "Groovy in Action", author: "Dierk Koenig")
}
assert books.toString() ==
    '{"books":{"book":{"title":"Groovy in Action",' +
    '"author":"Dierk Koenig"}}}'



• Groovy 1.7 introduced Grab resolver
– For when you need to specify a specific repository
for a given dependency

@GrabResolver(
name = 'restlet.org',
root = 'http://maven.restlet.org')
@Grab('org.restlet:org.restlet:1.1.6')
import org.restlet.Restlet


Power Asserts (1/2)

• Much better assert statement!
– Invented and developed in the Spock framework

• Given this script...

def energy = 7200 * 10**15 + 1
def mass = 80
def celerity = 300000000

assert energy == mass * celerity ** 2


Power Asserts (2/2)

• You’ll get a more comprehensible output


Easier AST Transformations

• AST Transformations are a very powerful feature

• But are still rather hard to develop
– Need to know the AST API closely

• To help with authoring your own transformations,
we’ve introduced
– the AST Viewer in the Groovy Console
– the AST Builder


AST Viewer


AST Builder

// Ability to build AST parts
// ‐‐> from a String
new AstBui lder().buildFromString(''' "Hello" ''')

// ‐‐> from code
new AstBuilder().buildFromCode { "Hello" }

// ‐‐> from a specification
{
List<ASTNo de> nodes = new AstBuilder().buildFromSpec
    block {
        returnStatement {
            constant "Hello"
        }
    }
}


Customize the Groovy Truth!

• Ability to customize the truth by implementing a
boolean asBoolean() method

class Predicate {
    boolean value
    boolean asBoolean() { value }
}

def tr uePred  = new Predicate(value: true)
def fals ePred = new Predicate(value: false)

assert truePred && !falsePred


Groovy 1.7.x changes

• Since Groovy 1.7.0...
Groovy 1.7.1, 1.7.2, 1.7.3, 1.7.4, 1.7.5 and 1.7.6
have been released already!

• Here’s what’s new!



• Groovy 1.7.5 even further shrinks the grab resolver
definition:

@Gra bResolver('http://maven.restlet.org')
@Grab('org.restlet:org.restlet:1.1.6')
import org.restlet.Restlet


Map improvements (1/2)

// map auto‐vification
def m = [:].withDefault { key ‐> "Default" }
assert m['z'] == "Default"
assert m['a'] == "Default"

// default sort, sort with a comparator
m.sort()
m.sort({ a, b ‐> a <=> b } as Comparator)

// max{} and min{}
assert [a: 1, b: 2].max{ it.value }.value == 2



// before Map#withDefault()

def words = "one two two three three three".split()

def freq = [:]

words.each {
    if (it in freq)
        freq[it] += 1
    else
        freq[it] = 1
}



// after Map#withDefault()

def words = "one two two three three three".split()

def freq = [:].withDefault { k ‐> 0 }

words.each {

freq[it] += 1

}


XML back to String

• Ability to retrieve the XML string from a node from
an XmlSlurper GPathResult

def xml = """
<books>
<book isbn="12345">Groovy in Action</book>
</books>
"""
def root = new XmlSlurper().parseText(xml)
def someNode = root.book
def bu ilder = new StreamingMarkupBuilder()

assert build er.bindNode(someNode).toString() ==
"<book isbn='12345'>Groovy in Action</book>"


Currying improvements

// right currying
def divide = { a, b ‐> a / b }
def halver = divide.rcurry(2)
assert halver(8) == 4

// currying n‐th parameter
def jo inWithSeparator = { one, sep, two ‐>
one + sep + two
}
def joinWithComma =
jo inWithSeparator.ncurry(1, ', ')
assert joinWithComma('a', 'b') == 'a, b'


Date improvements

im port static java.util.Calendar.*

// convert to calendar
def cal = new Date().toCalendar()

// update a date (or a calendar)
cal.set(year: cal[YEAR] + 1)
cal[MONTH] = MARCH

// create a ne w date (or a calendar) from one
def nextYear = c al.updated(year: cal[YEAR] + 1)


New String methods

println """ println """
    def method() {     |def method() {
        return 'bar'     |    return 'bar'
    }     |}
""".stripIndent() """.stripMargin('|')

// string "translation" (UNIX tr)
assert 'hello'.tr('z‐a', 'Z‐A') == 'HELLO'
WAAAA!'
asse rt 'Hello World!'.tr('a‐z', 'A') == 'HAAAA
2d!'
assert 'Hell o World!'.tr('lloo', '1234') == 'He224 W4r

// capitalize the first letter
assert 'h'.capitalize() == 'H'
assert 'hello'.capitalize() == 'Hello'
rld'
asse rt 'hello world'.capitalize() == 'Hello wo
mmand)
// tab/space (un)expansion (UNIX expand co
7 8        '
assert '1234567t8t '.expand() == '123456
'
assert '    x    '.unexpand() == '    xt


Map supports isCase()

def m = [a: 1, b: 2]
def val = 'a'

switch (val) {
    case m: "key in map"; break
    // equival ent to // case { val in m }: ...
    default: "not in map"
}


(G)String to Enum coercion

enum Color {
red, green, blue
}

// coercion with as
def r = "red" as Color

// implicit coercion
Color b = "blue"

// with GStrings too
def g = "${'green'}" as Color


...and beyond!

Groovy 1.8 & beyond

• Still subject to discussion
• Always evolving roadmap
• Things may change!


What’s cooking?

What we’re working on

• More runtime performance improvements
• Closures
– annotation parameters
composition, memoization, and trampoline
• Native JSON support
– builder and parser
• New AST transformations
• Gradle build
• Modularizing Groovy
• Align with JDK 7 / Java 7 / Project Coin
• Enhanced DSL support


An example, with Fibonacci



• Known example of worst case
performance for Groovy




• Groovy 1.7.5 vs Java
– 25131ms / 1110ms
–22x slower!




• Groovy 1.7.5 vs Java
– 25131ms / 1110ms
–22x slower!

• Groovy 1.8-beta-3 vs Java
– 1871ms / 1110ms
–only 68% slower




13 x • Groovy 1.7.5 vs Java
– 25131ms / 1110ms
–22x slower!

• Groovy 1.8-beta-3 vs Java
– 1871ms / 1110ms
–only 68% slower


Optimizations for int

• Currently, the optimizations cover most of native
operations on primitive ints
– Be careful, your mileage may vary

• To come next
– optimizations for doubles
– improving array accesses
– then other primitives optimizations
– and mixed cases of primitives


Closure annotation parameters

• Groovy 1.5 brought Java 5 annotations

• What if... we could go beyond what Java offered?
– In 1.7, we can put annotations on packages, imports and
variable declarations
– But annotations are still limited in terms of parameters
they allow

• Here comes closure annotation parameters!
– Groovy 1.8 will give us the ability to access annotation
with closure parameters at runtime


GContracts

• Closures are already allowed in the Groovy 1.7 Antlr
grammar
– André Steingreß created GContracts,
a «design by contract» module

// a class invariant
@Invar iant({ name.size() > 0 && age > ageLimit() })
class Person { String name; int age }

// a method pre‐condition
@Requires({ message != null })
void greet(String message) { ... }

// a method post‐condition
@Ensures({ returnResult % 2 == 0 })
int evenResult() { ... }

Closure composition

• Functional flavor!

def plus2 = { it + 2 }
def times3 = { it * 3 }

def composed1 = plus2 << times3
assert composed1(3) == 11
assert composed1(4) == plus2(times3(4))

def composed2 = times3 << plus2
assert composed2(3) == 15
assert composed2(5) == times3(plus2(5))

// reverse composition
assert composed1(3) == (times3 >> plus2)(3)


Closure memoization

• Memoization: remember the outcome of previous
(ideally side-effect free) invocations

def c = { a, b ‐> sleep 1000; a + b }.memoize()
assert c(1, 2) == 3 // after 1000ms
assert c(1, 2) == 3 // return immediately

// other forms:
// at least 10 invocations cached
def cAtLeast = { ... }.memoizeAtLeast(10)
// at most 10 invocations cached
def cAtMost = { ... }.memoizeAtMost(10)
// between 10 and 20 invocations cached
def cAtLeast = { ... }.memoizeBetween(10, 20)


Closure trampoline

• No more infamous StackOvervlow errors for deeply
recursive algorithms
– if you use closure trampolines explicitely

def fact
fact = { int n, BigInteger accu ‐>
    n > 1 ? fact.trampoline(n ‐ 1, n * accu) : accu
}.trampoline()

def factorial = { int n ‐> fact(n, 1G) }

assert factorial(1)    == 1
assert factorial(3)    == 6
assert factorial(1000) == 402387260077...


New AST xforms (1/2)

• Many new transformations coming up for
removing even more boiler plate code

@Log inject a logger in your classes
@Field creates a field in your scripts
@PackageScope improvements (methods & fields)
@Synchronized providing safer synchronization semantics
@InheritConstructor ex. when extending Exception
@IndexedProperties JavaBeans indexed property support
@AutoClone automatic cloning of your beans
@AutoExternalizable automatic externalization of your beans


New AST xforms (2/2)

@ThreadInterrupt makes a script interruptible
@TimedInterrupt interrupt after a period of time
@ConditionalInterrupt interrupt with a custom condition

@Canonical adds equals, hashCode, toString, ctor
- @EqualsAndHashCode just equals and hashCode
- @ToString just toString
- @TupleConstructor adds a «tuple» constructor


Java 7 / 8 / Project Coin

• Alignment with JDK 7 will come in Groovy 1.9
• JSR-292 InvokeDynamic
• Simple Closures (8)

• Proposals from Project Coin
– Strings in switch (7)
– Automatic Resource Management (7)
– Improved generics type inference (diamond <>) (7)
– Simplified varargs method invocation (7)
– Better integral literals (7)
– Language support for collections (8?)


Improved DSL support

• GEP-3: an extended command expression DSL
– Groovy Extension Proposal #3

• Command expressions
– basically top-level statements without parens
– combine named and non-named arguments in the mix
•for nicer Domain-Specific Languages
– (methodName arguments)*


Before GEP-3

• The idea: extend command-expressions, beyond
top-level statements, for chained method calls
• Before

send("Hello").to("Graeme")

check(that: margherita).tastes(good)

sell(100.shares).of(MSFT)

take(2.pills).of(chloroquinine).after(6.hours)

wait(10.minutes).and(execute { })

blend(red, green).of(acrylic)


With GEP-3

• After

send "Hello"  to "Graeme"

check that: margherita  tastes good

sell 100.shares  of MSFT

take 2.pills  of chloroquinine  after 6.hours

wait 10.minutes  and execute {  }

blend red, green  of acrylic


With GEP-3

• After
Less
& co pare
send "Hello"  to "Graeme"

check that: margherita  tastes good mm ns
sell 100.shares  of MSFT
as
take 2.pills  of chloroquinine  after 6.hours

wait 10.minutes  and execute {  }

blend red, green  of acrylic


The pattern

• A repetition of
– method name
– arguments (mix of named and normal)

check that: margherita tastes good
method method
named parameter parameter
name name


Summary

• No need to wait for Java 7, 8, 9...
– closures, properties, interpolated strings, extended
annotations, metaprogramming, [YOU NAME IT]...


Summary

• No need to wait for Java 7, 8, 9...
– closures, properties, interpolated strings, extended
annotations, metaprogramming, [YOU NAME IT]...

’s s till
Gro ovy
novat ive
in
20 03!
si nce

d A
a n
Q

Copyright 2010 SpringSource. Copying, publishing or distributing without express written permission is prohibited.


Picture credits

Myself http://www.flickr.com/photos/romainguy/783719255/sizes/l/in/photostream/
Big hat http://cdn.plussizecostumesupercenter.com/csc_inc/images/items/343x432/47703.jpg
RIP http://gipsydan.files.wordpress.com/2009/11/rip.jpg
House / past: http://www.flickr.com/photos/jasonepowell/3680030831/sizes/o/
Present clock: http://www.flickr.com/photos/38629278@N04/3784344944/sizes/o/
Future: http://www.flickr.com/photos/befuddledsenses/2904000882/sizes/l/
Cooking: http://www.flickr.com/photos/eole/449958332/sizes/l/
Snail http://www.freakingnews.com/images/app_images/snail-0.jpg
Usein bolt record http://www.phombo.com/sports/usain-bolt-beijing-2008-olympics/17450/full/popular/
Fibonacci figure http://cnx.org/content/m22060/latest/graphics1.jpg
Fibonacci face http://www.robinkelly.co.nz/site/acupil/images/lfib.jpg
Puzzle: http://www.everystockphoto.com/photo.php?imageId=263521
Light bulb: https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.png
Check mark: http://www.lnl.infn.it/~epics/WikiDumps/localhost/600px-symbol_ok.svg.png
Puzzle: http://www.everystockphoto.com/photo.php?imageId=263521
Light bulb: https://newsline.llnl.gov/retooling/mar/03.28.08_images/lightBulb.png
Green leaf: http://www.flickr.com/photos/epsos/3384297473/
Trafic light: http://rihancompany.com/var/243/35581-Traffic%20light%20drawing.jpg
Butt kick: http://www.brentcsutoras.com/wp-content/uploads/2009/12/kick-ass-1.jpg


Groovy 1.7 and 1.8 Progress

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