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![Rich types
Scala Python
Array Array(1,2,3,4) (1,2,3,4]
Tuple (1,2,3,4) (1,2,3,4)
List List(1,2,3,4) (1,2,3,4)
Map Map(“a”>1, “b”>2) {“a”:1, “c”:2}
Set Set(1,2,3,4) set(1,2,3,4)
ffunction
inc.](https://image.slidesharecdn.com/mtlpy-flash-scala-110729162925-phpapp01/75/From-Python-to-Scala-9-2048.jpg)
![Closures
[1,2,3] map { i => i + 1 }
{i:Int => i + 1 } # 1-param normal
(i:Int) => { i + 1 } # n-param normal
[1,2,3] map { _ + 1 } # implicit args
val f = { i:Int => i + 1}
ffunction
inc.](https://image.slidesharecdn.com/mtlpy-flash-scala-110729162925-phpapp01/75/From-Python-to-Scala-10-2048.jpg)
![Batteries included
scala.xml.XML.load(
"http://ffunction.posterous.com/rss.xml"
) "item" "title" toList
List[scala.xml.Node] = List(<title xmlns:media="http://search.yahoo.com/mrss/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:posterous="http://posterous.com/help/rss/1.0"
xmlns:atom="http://www.w3.org/2005/Atom">Notes on creating a multitouch
interface</title>, <title xmlns:media="http://search.yahoo.com/mrss/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:posterous="http://posterous.com/help/rss/1.0"
xmlns:atom="http://www.w3.org/2005/Atom">Formations en interface &
visualisation</title>, <title xmlns:media="http://search.yahoo.com/mrss/"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:posterous="http://posterous.com/help/rss/1.0"
xmlns:atom="http://www.w3.org/2005/Atom">Hello, world !</title>)
ffunction
inc.](https://image.slidesharecdn.com/mtlpy-flash-scala-110729162925-phpapp01/75/From-Python-to-Scala-16-2048.jpg)
![The almost ML-grade type system
val f:List[Int] = List[1,2,3]
val m:Map[String,List[Int]] = Map(
“a” → [1,2,3],
“b” → [4,5,6]
)
type JSONable = { def toJSON():String }
> ensure constraints at compile-type, speed up programs
ffunction
inc.](https://image.slidesharecdn.com/mtlpy-flash-scala-110729162925-phpapp01/75/From-Python-to-Scala-19-2048.jpg)
![Multiple method dispatch
def merge( def merge(
a:Map[String,Object], a:List[Object],
b:Map[String,Object] b:List[Object]
):Map[String,Object] ):List[Object]
> makes it easy to specialize (existing) libraries
ffunction
inc.](https://image.slidesharecdn.com/mtlpy-flash-scala-110729162925-phpapp01/75/From-Python-to-Scala-20-2048.jpg)
Uploaded byFFunction inc
From Python to Scala
This document summarizes a presentation about moving from Python to Scala. It highlights things that are missed in Python like closures and easy concurrency. Scala is described as a compiled and interpreted language that runs on the JVM and is both object-oriented and functional. Key features of Scala discussed include its powerful type system, support for immutable data structures, pattern matching, actors model for concurrency, and ability to interface with Java libraries. In conclusion, Scala is said to be very powerful but also difficult to learn, making it a good complement to Python for performance-critical or scalable projects.
More Related Content
From Python to Scala
- 1. From Python to Scala Sébastien Pierre, ffunction inc. @Montréal Python, April 2010 www.ffctn.com ffunction inc.
- 2. Stuff I loveabout Python ● Expressive (and compact) ● Simple to learn ● Lots of smartly designed libraries ffunction inc.
- 3. Stuff that Imiss in Python ● Closures (with syntax) ● Easy concurrency (model and syntax) ● … a compiler !! ffunction inc.
- 4. Scala - overview ffunction inc.
- 5. The language ● JVM-based, compiled + « interpreted » ● Functional + OO (post-functional) ● ~6 years old ● used by Twitter, FourSquare ffunction inc.
- 6. The library ● Anything in Java ● Immutable types library (safe for concurrent apps) ● Concurrency + actor model ● Quality community-contributed libraries ffunction inc.
- 7. The feel ● Make do with braces ● map/filter/apply (and fold) ● ~25% more lines than with Python ● Very good DSL-ability ● Fast ! ffunction inc.
- 8. Scala – basics ffunction inc.
- 9. Rich types Scala Python Array Array(1,2,3,4) (1,2,3,4] Tuple (1,2,3,4) (1,2,3,4) List List(1,2,3,4) (1,2,3,4) Map Map(“a”>1, “b”>2) {“a”:1, “c”:2} Set Set(1,2,3,4) set(1,2,3,4) ffunction inc.
- 10. Closures [1,2,3] map { i => i + 1 } {i:Int => i + 1 } # 1-param normal (i:Int) => { i + 1 } # n-param normal [1,2,3] map { _ + 1 } # implicit args val f = { i:Int => i + 1} ffunction inc.
- 11. Classes + traits classA {…} ffunction inc.
- 12. Classes + traits class A {…} class B extends A {…} ffunction inc.
- 13. Classes + traits class A {…} class B extends A trait T with T {…} {…} ffunction inc.
- 14. Classes + traits class A trait U {…} {…} class B trait T extends A extends U with T {…} {…} ffunction inc.
- 15. Classes + traits class A trait U {…} {…} class B trait T extends A extends U with T {…} {…} ffunction inc.
- 16. Batteries included scala.xml.XML.load( "http://ffunction.posterous.com/rss.xml" ) "item" "title" toList List[scala.xml.Node] = List(<title xmlns:media="http://search.yahoo.com/mrss/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:posterous="http://posterous.com/help/rss/1.0" xmlns:atom="http://www.w3.org/2005/Atom">Notes on creating a multitouch interface</title>, <title xmlns:media="http://search.yahoo.com/mrss/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:posterous="http://posterous.com/help/rss/1.0" xmlns:atom="http://www.w3.org/2005/Atom">Formations en interface & visualisation</title>, <title xmlns:media="http://search.yahoo.com/mrss/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:posterous="http://posterous.com/help/rss/1.0" xmlns:atom="http://www.w3.org/2005/Atom">Hello, world !</title>) ffunction inc.
- 17. Interpreter scala> println( List("Hello","world !") match { case head :: tail => tail.foldLeft(head)( (a:String,b:String)=>{a+", " +b})}) Hello, world ! ffunction inc.
- 18. Scala – thesublime* *SUBLIME : pleasure + pain, according to the Romantics ffunction inc.
- 19. The almost ML-gradetype system val f:List[Int] = List[1,2,3] val m:Map[String,List[Int]] = Map( “a” → [1,2,3], “b” → [4,5,6] ) type JSONable = { def toJSON():String } > ensure constraints at compile-type, speed up programs ffunction inc.
- 20. Multiple method dispatch defmerge( def merge( a:Map[String,Object], a:List[Object], b:Map[String,Object] b:List[Object] ):Map[String,Object] ):List[Object] > makes it easy to specialize (existing) libraries ffunction inc.
- 21. Pattern-matching val sum ={ _ match { case head :: tail > head + sum (tail) case Nil > 0 } } > amazing for message-based communication and list manipulation ffunction inc.
- 22. Actors import scala.actors.Actor._ actor { while (true) {println ("Hello from A") ; Thread.sleep(1)} } actor { while (true) {println ("Hello from B") ; Thread.sleep(1)} } Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from B Hello from B Hello from B Hello from B Hello from B Hello from B Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from B Hello from B Hello from B Hello from B Hello from B Hello from B Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from B Hello from B Hello from B Hello from B Hello from B Hello from B Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from B Hello from B Hello from B Hello from B Hello from B Hello from B Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from B Hello from B Hello from B Hello from B Hello from B Hello from B Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A Hello from B Hello from B Hello from B Hello from B Hello from B Hello from B Hello from A Hello from A Hello from A Hello from A Hello from A Hello from A ffunction inc.
- 23. Message-passing import scala.actors.Actor._ val repeater= actor { while (true) { receive { case msg:String => println(this + ">" + msg) ; reply (msg) }}} actor { repeater ! "ping" while (true) { receive { case msg:String => println(this + ">" + msg) ; reply (msg) }}} ffunction inc.
- 24. Le mot dela fin ffunction inc.
- 25. Scala is cool! ● Very powerful ● Hard to learn, long time to master ● Amazing complement to Python for research & performance-critical and scalable projects ● Easy to interface with Python ! ffunction inc.
- 26. Merci ! www.ffctn.com sebastien@ffctn.com ffunction inc.