Polyglot Programming @ Jax.de 2010

Andres Almiray | Canoo Engineering AG Polyglot Programming in the JVM Or how I Learned to Stop Worrying and Love the JVM

About the speaker   Java developer since the beginning   True believer in open source   Groovy committer since 2007   Project lead of the Griffon framework   Currently working for

Some facts about Java   Previous name was Oak. Bonus points for knowing its real name before that   Made its public appearance in 1995   C/C++ were king at the time   Networking, multithreading were baked right into the language   Developers came for the applets and stayed for the components (JEE and all that jazz)

However...   It is already in its teens   It has not seen a major feature upgrade since JDK5 was released back in 2004 -> generics (and we do know how that turned out to be, don’t we?)   JDK7 has been delayed again (late 2010). Some features might or might not make the cut (the closures debacle)

More so...   It is rather verbose when compared to how other languages do the same task   Its threading features are no longer enough. Concurrent programs desperately cry for immutability these days

Truth or myth?   Is Java oftenly referred as overengineered?   Can you build a Java based web application (for arguments sake a basic Twitter clone) in less than a day‘s work WITHOUT an IDE?   Did James Gosling ever say he was threatened with bodily harm should operator overloading ﬁnd its way into Java?

The JVM is a great place to work however Java makes it painful sometimes...

Disclaimer (this is not a bash-the-other-languages talk)

Standard Beans public class Bean { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } }

Standard Beans class Bean { String name }

Standard Beans class Bean(var name:String) class Bean { @scala.reflect.BeanProperty var name: String }

Standard Beans (defstruct Bean :name)

Closures (or Functions) public interface Adder { int add(int a, int b); } public class MyAdder implements Adder { public int add(int a, int b) { return a + b; } }

Closures (or Functions) def adder = { a , b -> a + b }

Closures (or Functions) def adder(a: Int, b: Int) = a + b

Closures (or Functions) (defn adder [a b] (+ a b))

Enhanced switch char letterGrade(int grade) { if(grade >= 0 && grade <= 60) return ‘F‘; if(grade > 60 && grade <= 70) return ‘D‘; if(grade > 70 && grade <= 80) return ‘C‘; if(grade > 80 && grade <= 90) return ‘B‘; if(grade > 90 && grade <= 100) return ‘A‘; throw new IllegalArgumentException(‘invalid grade ‘+grade); }

Enhanced Switch def letterGrade(grade) { switch(grade) { case 90..100: return ‘A‘ case 80..<90: return ‘B‘ case 70..<80: return ‘C‘ case 60..<70: return ‘D‘ case 0..<60: return ‘F‘ case ~"[ABCDFabcdf]": return grade.toUpperCase() } throw new IllegalArgumentException (‘invalid grade ‘+grade) }

Enhanced Switch val VALID_GRADES = Set("A", "B", "C", "D", "F") def letterGrade(value: Any):String = value match { case x:Int if (90 to 100).contains(x) => "A" case x:Int if (80 to 90).contains(x) => "B" case x:Int if (70 to 80).contains(x) => "C" case x:Int if (60 to 70).contains(x) => "D" case x:Int if (0 to 60).contains(x) => "F" case x:String if VALID_GRADES(x.toUpperCase) => x.toUpperCase() }

Enhanced Switch (defn letter-grade [grade] (cond (in grade 90 100) "A" (in grade 80 90) "B" (in grade 70 80) "C" (in grade 60 70) "D" (in grade 0 60) "F" (re-find #"[ABCDFabcdf]" grade) (.toUpperCase grade)))

All of these are true   Java can call Groovy, Scala and Clojure classes as if they were Java classes   Groovy, Scala and Clojure can call Java code without breaking a sweat   In other words, interoperability with Java is a given. No need for complicated bridges between languages (i.e. JSR 223)

Ok, so... What else can these languages do?

All of them   Native syntax for collection classes   Everything is an object   Closures!   Regular expressions as ﬁrst class citizens   Operator overloading

Groovy   Metaprogramming (HOT!) both at buildtime and runtime   Builders   Healthy ecosystem: Grails, Griffon, Gant, Gradle, Spock, Gaelyk, Gpars, CodeNarc, etc...    Not an exhaustive list of features!

Scala   Richer type system   Type inference   Pattern matching (case classes)   Actor model    Not an exhaustive list of features!

Clojure   Data as code and viceversa   Immutable structures   STM    Not an exhaustive list of features!

Other places where you‘ll ﬁnd Polyglot Programming

Web app development   XML   SQL   JavaScript   JSON   CSS   Flash/Flex/ActionScript

Next-Gen datastores (NoSQL)   FleetDB -> Clojure    FlockDB -> Scala    CouchDB, Riak -> Erlang   btw watch out for Polyglot Persistence ;-)

Build systems   Gradle, Gant -> Groovy    Rake -> Ruby/JRuby    Maven3 -> XML, Groovy, Ruby

Parting thoughts   Java (the language) may have reached its maturity feature wise   Other JVM languages evolved faster   Polyglot Programming is not a new concept   Download and play with each of the demoed languages, maybe one of them strikes your fancy

Polyglot Programming @ Jax.de 2010

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Polyglot Programming @ Jax.de 2010