BP203 limitless languages

BP203 Limitless Languages In The
IBM Social Stack
Mark Myers | London Developer Coop

© 2013 IBM Corporation

Agenda

Overview

The JVM

Programming paradigms

JVM Alternative Languages

Scala

Existing Code

Working With Domino


This presentation skims over the hard work and dedication of
thousands of developers passions, any generalizations or
sweeping statements are not intended to give offense,
corrections are gratefully received.

But most of all please interrupt!

Don't wait till the end of the session


Who Am I?

 Mark
Member of the London Developer Co-op (londc.com)
Developer from a support background
12+ years on Domino, 15+ years in IT
Speaker at 2x Lotuspheres, 3x UKLUGs, 1x ILUG
Twitter: @stickfight, Skype: Stickfight, Blog: stickfight.co.uk


Tools We Used

 IBM® Lotus® Notes® version 8.5.3

 IBM Lotus Domino® version 8.5.3

 Eclipse 3.7 (indigo)

 Scala plug-in 29

 Various other software tools mentioned
throughout this presentation
 Most code and techniques we talk about should be applicable to other versions of
Notes/Domino/Windows too


Limitless Languages?

Limitless Languages
=
Alternative JVM Languages

Alternative JVM Languages
=
Any Language that Compiles to Java ByteCode


Why this Session?

Existing and Traditional IT cant keep up with the speed of green field and start-up
development

You need little or no Investment to get started and you don’t have to throw your
existing Java stuff away

Its not all up to IBM to keep us up to date. Nearly all of you are
already using an
Never get left behind again
IBM alternative JVM
Its simple and helps your CV Language (sort of)

Its Cool


The JVM

The JVM (Java Virtual Machine) runs Java ByteCode

It’s Increased in reliability and performance since 1996

All variations of the JVM guarantees binary compatibility

Java ByteCode does NOT have to have been generated from Java, any Language
that compiles down to ByteCode can run on the JVM

We will take a look at the Pack Leaders

After some boring stuff


Dynamic Vs Static typed: Dynamic
In a dynamically typed language, every variable name is (unless it is null) bound
only to an object.

Names are bound to objects at execution time by means of assignment
statements, and it is possible to bind a name to objects of different types during
the execution of the program.

This does not cause an error,
unless you for get which type
LotusNotes = 8.5.4 the variable currently is
LotusNotes = “Awesome”


Dynamic Vs Static typed: Static

In a statically typed language, every variable name is bound both to a type (at
compile time) and to an object.

Once a variable name has been bound to a type (that is, declared) it can be bound
(via an assignment statement) only to objects of that type; it cannot ever be bound
to an object of a different type. An attempt to bind the name to an object of the
wrong type will raise a type exception.


Functional Programming A method of
coding like
Object Oriented
Programming

“functional programming is a programming paradigm that treats computations as the
evaluation of mathematical functions and avoids state and mutable data.”
-Wikipedia

Think of the states An object which
a document goes can be modified
through after it is
created


Functional Programming

Why?
Grants us greater modularity

Means code reuse and maintenance is easier

Immutable objects allows data to be accessed concurrently from multiple threads
without locking


An agile and dynamic language

A Core of Java with lots of features inspired by languages like Python, Ruby and
Smalltalk

Very small-zero learning curve

provides the ability to statically type check and statically compile your code ( good
for speed)

Seamlessly integrates with all existing Java classes and libraries i.e. unlike a lot of
other Alternative JVM languages you can include Java code in the same file as
Groovy

One of Groovy's top companions is Grails, a high-productivity web development
environment inspired by Ruby on Rails. not much use for domino designers but fab
if you are having to build your own UI (used by sky)



A general-purpose dynamic programming language

Is a dialect of Lisp

Also runs on Microsoft's Common Language Runtime and JavaScript engines.

Used by Citigroup, Typewire, Tianya (largest forum in china), AltLaw.org (one of
the first production websites to use it)



JRuby is an implementation of the Ruby programming language

JRuby is held to be faster than Ruby for most implementations (once loading the
JVM is taken into consideration)

Jruby is called from Java using either the JSR 223 Scripting for Java 6 or the
Apache Bean Scripting framework

LinkedIn uses JRuby for its front end



Jython the successor of JPython is an implementation of Python

Supports nearly all of the Core Python standard library modules and all Java Libs

Jython programs cannot currently use CPython extension modules written in C
(although this is supposedly coming)

Wsadmin (webSphere Server command shell) and Bea WebLogic use Jython as
their scripting language



Kotlin

Rhino

This is the Actual Logo


Scala

Stands for “scalable language.” named for its ability to grow with user needs

Designed by Martin Odersky, creator of Pizza (the forerunner of Java generics),
author of GJ compiler

"... if someone had shown me the Programming in Scala book ... back in 2003, I'd
probably have never created Groovy."
- James Strachan, July 2009


Scala

Under active development at Ecole Polytechnique Fédérale
de Lausanne (EPFL) and in the open source community,
also nicely funded by none corporations.

Programming in Scala second edition by Martin Odersky,
Lex Spoon and Bill Venners

http://www.artima.com/shop/programming_in_scala_2ed


Who Uses Scala?

LinkedIn Siemens

Twitter Électricité de France (EDF)

FourSquare The Guardian

Sony Xerox

IBM knows about it too, see Adrian Spender excellent
presentation at
http://www.slideshare.net/aspender/scala-introduction-6963846

And from IBM them selves
http://www.ibm.com/developerworks/training/kp/j-kp-altlang/index.html


Why?: Shorter / Less Boiler
// this is Java
class MyClass {
private int index;
private String name;

public MyClass(int index, String name) {
this.index = index;
this.name = name;
}
}

// this is Scala
class MyClass(index: Int, name: String)

http://stackoverflow.com/questions/2952732/samples-of-scala-and-java-code-
where-scala-code-looks-simpler-has-fewer-lines for an extreme example


Why?: Type Inference
Java – Static Type
Good – Catch type errors BEFORE you run
BAD – Verbose, bulky

Scripting Languages
Good – Short , easy to code
BAD – You get to catch your errors in test/production

Scala (with Type Inference)
Good – Catch Type Errors BEFORE you run
Good – Short , easy to code


Why?: Type Inference
You don’t have to assign a type
here, it infers this from type of
data you try and put in the
variable

val cost = new BigInteger("99999999")
var stringcost = List("nine", "nine")
Stringcost += cost

But Compiler still says no, when
you assign the wrong type


Why?: Unified types
All types are objects. (Int, Boolean,Double etc etc)

No more primitives ( no more double and Double)

All Mapped Automatically for integration with Java

All functions get the nice add-ons like toInt and toFloat for String


Why?: Pattern matching

Not Limited to primitives

You can even call Class and Functions :-)


Why?: Actors

Concurrency Made simple

Designed to get over the fundamental problems with Javas shared data and locks
model

It is a share-nothing model all communication is doing by messaging

An actor is a bit like a thread with a mailbox for receiving messages


Why?: Actor example


Why?: Parallel Processing
How do you make this run in parallel?


Why?: Parallel Processing

Now running in parallel

Calling thread WAITS for completion of computation

2 CPU Machine = 2 items running in parallel

Sanity Warning! : Scalaz
Danger Will
Robinson

A Plug in Library for Scala

An implementation of pure functional programming with very high-level
abstractions represented by symbols

Awesomely powerful and concise but a steep learning curve unless you are
familiar with the complexity and are dealing with things like Trading platforms

http://code.google.com/p/scalaz/


Sanity Warning! : Scalaz

:'-(


Cross Language Dependency

Existing Code


Cross Language Dependency
After Inclusion of a new Scala Class


Installing

Scala has plug-ins for Eclipse, IntelliJIDEA and NetBeans ( http://www.scala-
lang.org/node/91 )

I use http://scala-ide.org/ for the eclipse plug-in

Install Eclipse 3.6 (Helios) or Eclipse 3.7 (Indigo) and install as a standard plug-in
site (http://download.scala-ide.org/releases-29/stable/site )

Restart and you’re done


Nice and Simple in Eclipse


Working in Domino

Copy these 3 files to your ..jvmlibext directory (they are about 9meg in total and
cause a noticeable pause if in the agent)

Restart and you’re done


Working in Domino
Normal Java
Class doing
Stuff in Domino


Working in Domino
Scala Class, containing an Scala Object, calling that Java Class


Working in Domino

Export Class files to a Jar


Working in Domino

Import Jar file into
normal Agent


Working in Domino

Calling the Scala
Object from Within
a Java Agent


Working in Domino

Be Still my beating
heart!!!


Questions?
Mark Myers
London Developer Coop
mark@energywins.co.uk
Twitter: @stickfight


Legal disclaimer
• © IBM Corporation 2013. All Rights Reserved.
• The information contained in this publication is provided for informational purposes only. While efforts were made to verify the completeness and accuracy of the information contained in this publication, it is
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warranties or representations from IBM or its suppliers or licensors, or altering the terms and conditions of the applicable license agreement governing the use of IBM software.
• References in this presentation to IBM products, programs, or services do not imply that they will be available in all countries in which IBM operates. Product release dates and/or capabilities referenced in this
presentation may change at any time at IBM’s sole discretion based on market opportunities or other factors, and are not intended to be a commitment to future product or feature availability in any way. Nothing
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45 © 2013 IBM Corporation

THANK YOU!
Mark Myers
London Developer Coop
mark@energywins.co.uk
Twitter: @stickfight


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