Post on 10-May-2015
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Welcome to the Scalable Language
Ahmed SolimanFounder and Chairman
noZom NGO
Tuesday, May 24, 2011
@AhmedSoliman
AhmedSoliman.com
Asoliman@nozom.org
Tuesday, May 24, 2011
Martin OderskySwitzerland
Tuesday, May 24, 2011
@odersky
✦ 52 years old
✦ Pizza Programming language
✦ Generic Java
✦ Scala 2001
Tuesday, May 24, 2011
What is Scala?
Tuesday, May 24, 2011
What is Scala?
✦ Pronounced ‘skah-lak’
✦ Scalable Language
✦ Tastefully typed language
✦ Blend of object-oriented and functional programming
Tuesday, May 24, 2011
What is Scala?
✦ Uses the glorious JVM
✦ Can be used as scripting language
✦ Compiled!
✦ Everything is an expression!
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Expression vs. Statement
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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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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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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
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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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What’s functional?
✦ Functions return a value, given a set of parameters a function has one possible result.
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Two Main Ideas: I
Functions are first-class citizens
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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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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
Tuesday, May 24, 2011
This is Java
Tuesday, May 24, 2011
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
Tuesday, May 24, 2011
Referential Transparency
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State is the evil!Pun intended
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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
Tuesday, May 24, 2011
Why Scala?
Tuesday, May 24, 2011
Why Scala?✦ The Java Virtual Machine
✦ Concise (programs are shorter)
Tuesday, May 24, 2011
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
Tuesday, May 24, 2011
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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Mapping
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Reducing
21
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Pattern Matching
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Currying
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Concurrency
✦ Actor model! (kinda like erlang)
✦ Threads
✦ Any other JVM concurrency framework (Netty, Apache Mina, etc.)
Tuesday, May 24, 2011
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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Actors :: Performance✦ Apache (C/Threads) vs. Yaws (Erlang/Actor)
Tuesday, May 24, 2011
Actors :: Simpler
✦ Code is design around single-threaded mind
✦ No Mutable State
✦ No (Dead) lock
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Language Tour
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What for?
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✦ Scripting
✦ Concurrent Applications
✦ Web Development (Lift)
✦ Backend Components
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Who uses Scala?
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Summary✦ Fast
✦ Reuses the Java Ecosystem
✦ Functional
✦ Expressive
✦ Statically typed
✦ Concurrent
✦ Has tons of features, complex? Worth it!
Tuesday, May 24, 2011