The document summarizes Scala, a functional programming language that runs on the Java Virtual Machine (JVM). It discusses Scala's core features like being object-oriented, type inference, and support for functional programming with immutable data structures and passing functions as parameters. It also provides examples of using Scala collections like List and Array, and functions like map, filter, flatMap, and foldLeft/reduceLeft. Finally, it demonstrates using Scala for domain-specific languages and shows examples of defining DSLs for querying and generating JavaScript.

1. Beginning Scala David Pollak Silicon Valley Code Camp October 3rd, 2009

3. Lead developer for Lift web framework

4. Scala since November 2006, Ruby/Rails, Java/J2EE

5. Spreadsheet junky (writing more than using)

6. Wrote Beginning Scala

9. 100% compatible with Java objects

11. Type inferencing

12. Super-easy to pass functions as parameters

13. Scala in the Wild

14. At the command line

16. Linked List of type T (String, Int, FooClass)

18. Thin veneer on JVM Array

19. Lots of methods (map, filter, toList, etc.)

20. Collections

22. Return a new collection containing the result

24. Return a new collection containing items that passed

25. map & filter

27. Useful for nesting operations on collections

28. "99 red balloons".toList List[Char] = List(9, 9, , r, e,...)

29. List("99 red balloons", "88 lines", "44 women"). flatMap(s => s.filter(Character.isDigit)) List[Char] = List(9, 9, 8, 8, 4, 4)

31. Good for: sum, product, etc.

32. List(1,2,3,4).reduceLeft(_ + _) Int = 10

33. def sq(in: Int) = in * in def sum(in: List[Int]) = in.foldLeft(0)(_ + _) def sumSq(in: List[Int]) = sum(in.map(sq)) def sqSum(in: List[Int]) = sq(sum(in))

36. Calculator in Action

38. SetValById(inputName, "") & SetValById(hiddenName, "") & SetElemById(clrLinkName, "none", "style.display")

39. <button onclick={ jsonCall(&quot;submit&quot;, JsArray(ValById(inputName), ValById(hiddenName)))}>Yep</button>

41. def find(by: QueryParam[A]*) abstract class QueryParam[A<:Mapper[A]] case class Cmp[A<:Mapper[A], T](...) extends QueryParam[A] object By { import OprEnum._ def apply[O <: Mapper[O], T, U <% T](...) = Cmp[O,T](field, Eql, Full(value), Empty)

43. trait JsCmd extends HtmlFixer with ToJsCmd { def &(other: JsCmd): JsCmd = JsCmds.CmdPair(this, other) def toJsCmd: String }