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Welcome to the Scalable Language

Ahmed SolimanFounder and Chairman

noZom NGO

Tuesday, May 24, 2011

@AhmedSoliman

AhmedSoliman.com

[email protected]


mailto:[email protected]

mailto:[email protected]

Martin OderskySwitzerland


@odersky

✦ 52 years old

✦ Pizza Programming language

✦ Generic Java

✦ Scala 2001


What is Scala?


What is Scala?

✦ Pronounced ‘skah-lak’

✦ Scalable Language

✦ Tastefully typed language

✦ Blend of object-oriented and functional programming


What is Scala?

✦ Uses the glorious JVM

✦ Can be used as scripting language

✦ Compiled!

✦ Everything is an expression!


Expression vs. Statement


Grows on you

✦ Looks like modern dynamically typed languages (Python, Ruby, etc.)

✦ Unlike Python, maps in scala is not a language syntax! {‘key’: ‘value’}


Growing new types

✦ BigInt looks like a built-in type, because you can use integer literals and operators such as (*, -, and +) with values of that type


What makes Scala scalable?

✦ Scala is object oriented in pure form!

✦ Every value is an object and every operation is a method call

✦ Scala is full-blown functional programming language


Functional?

✦ Lisp late 50s

✦ Scheme, SML, Erlang, Haskell, OCaml, and F#

✦ For long time, popular in academia, but not in industry


What’s functional?

✦ Functions return a value, given a set of parameters a function has one possible result.


Two Main Ideas: I

Functions are first-class citizens


Citizens?

✦ A function is a value of the same status as, say, an integer or a string.

✦ You can pass functions as arguments to other functions

✦ Return functions as a results from functions

✦ Store them in variables


Functions, citizens?

✦ You can define functions without giving them a name, sprinkling your code with function literals as easy as integer literals, like 25

✦ A good example is the pain in writing code for event handling in java


This is Java


Two Main Ideas: II

✦ Operations of a program should map input values to output values rather than change data in place

✦ Consider the difference between Strings in Java and Ruby!

✦ Immutable data structures are the cornerstone of functional programming


Referential Transparency


State is the evil!Pun intended


Multi-core problems✦ The future!

✦ Threading is damn hard to get right

✦ Memory overhead

✦ Dead locks?

✦ Shared state? Monitor? Mutex? Semaphore?

✦ Demand for highly concurrent application is increasing


Why Scala?


Why Scala?✦ The Java Virtual Machine

✦ Concise (programs are shorter)


Why Scala??✦ A rich static type system that gets out of your

way when you don’t need it, is awesome when you do. (Type Inference). Verifiable!

✦ Flexible syntax

✦ Immutable and mutable variables


Why Scala??

✦ Functional programming features: mapping, filtering, folding, currying, so much more.

✦ FAST! (most of the times as fast as Java)

✦ Can call any Java code

✦ Can be called by any Java code


Mapping


Reducing

21


Pattern Matching


Currying


Concurrency

✦ Actor model! (kinda like erlang)

✦ Threads

✦ Any other JVM concurrency framework (Netty, Apache Mina, etc.)


Concurrency :: Actor✦ Actor Mode: a different way to implement

concurrency

✦ Each object is an actor

✦ Each actor has a mailbox

✦ Actors (asynchronously) send messages and receive them in their mailbox

✦ No Shared State

✦ Why?


Actors :: Performance✦ Apache (C/Threads) vs. Yaws (Erlang/Actor)


Actors :: Simpler

✦ Code is design around single-threaded mind

✦ No Mutable State

✦ No (Dead) lock


Language Tour


What for?


✦ Scripting

✦ Concurrent Applications

✦ Web Development (Lift)

✦ Backend Components


Who uses Scala?


Summary✦ Fast

✦ Reuses the Java Ecosystem

✦ Functional

✦ Expressive

✦ Statically typed

✦ Concurrent

✦ Has tons of features, complex? Worth it!


www.nozom.orgTuesday, May 24, 2011

http://www.nozom.org

http://www.nozom.org

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