The document is a presentation on the Scala programming language. It introduces Scala as a scalable, statically typed language that blends object-oriented and functional programming. Some key features highlighted include running on the JVM, first-class functions, immutable data structures, pattern matching, and using an actor model for concurrency. Examples are provided to illustrate concepts like mapping, reducing, currying and actors. The presenter argues that Scala is fast, leverages Java libraries, is highly expressive yet statically typed, and facilitates concurrent programming.

1. Welcome to the
Scalable Language
Ahmed Soliman
Founder and Chairman
noZom NGO
Tuesday, May 24, 2011

2. AhmedSoliman.com
Asoliman@nozom.org
@AhmedSoliman
Tuesday, May 24, 2011

3. Martin Odersky
Switzerland
Tuesday, May 24, 2011

4. ✦ 52 years old
✦ Pizza Programming
language
✦ Generic Java
✦ Scala 2001
@odersky
Tuesday, May 24, 2011

5. What is Scala?
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6. What is Scala?
✦ Pronounced ‘skah-lak’
✦ Scalable Language
✦ Tastefully typed language
✦ Blend of object-oriented and functional
programming
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7. What is Scala?
✦ Uses the glorious JVM
✦ Can be used as scripting language
✦ Compiled!
✦ Everything is an expression!
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8. Expression vs. Statement
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9. Grows on you
✦ Looks like modern dynamically typed
languages (Python, Ruby, etc.)
✦ Unlike Python, maps in scala is not a language
syntax! {‘key’: ‘value’}
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10. 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
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11. 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
Tuesday, May 24, 2011

12. Functional?
✦ Lisp late 50s
✦ Scheme, SML, Erlang, Haskell, OCaml, and
F#
✦ For long time, popular in academia, but not in
industry
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13. What’s functional?
✦ Functions return a value, given a set of
parameters a function has one possible result.
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14. Two Main Ideas: I
Functions are first-class citizens
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15. 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
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16. 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
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17. This is Java
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18. 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
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19. Referential
Transparency
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20. State is the evil!
Pun intended
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21. 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
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22. Why Scala?
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23. Why Scala?
✦ The Java Virtual Machine
✦ Concise (programs are shorter)
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24. 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
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25. 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
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26. Mapping
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27. Reducing
21
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28. Pattern Matching
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29. Currying
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30. Concurrency
✦ Actor model! (kinda like erlang)
✦ Threads
✦ Any other JVM concurrency framework
(Netty, Apache Mina, etc.)
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31. 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?
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32. Actors :: Performance
✦ Apache (C/Threads) vs. Yaws (Erlang/Actor)
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33. Actors :: Simpler
✦ Code is design around single-threaded mind
✦ No Mutable State
✦ No (Dead) lock
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34. Language Tour
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45. What for?
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46. ✦ Scripting
✦ Concurrent Applications
✦ Web Development (Lift)
✦ Backend Components
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47. Who uses Scala?
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54. Summary
✦ Fast
✦ Reuses the Java Ecosystem
✦ Functional
✦ Expressive
✦ Statically typed
✦ Concurrent
✦ Has tons of features, complex? Worth it!
Tuesday, May 24, 2011

55. www.nozom.org
Tuesday, May 24, 2011