This document summarizes some of the good parts of the Scala language based on feedback from Java developers who have used Scala. It highlights features like type inference, expression syntax everywhere, case classes, pattern matching, functions, the ecosystem including REPL, libraries, frameworks and tools, concurrency with actors, and the strengths of the type system. It also provides some warnings about using features like implicits and annotations wisely.

1. Scala
The Good Parts
@
http://afoo.me

2. also the SimpleParts

3. The
Good
Parts
Of
The
Language

4. –the guys who came from Java to Scala said
“
(I will never turn back to Java
any more)”

5. farewell, semi-colon

6. Type Inference

7. 类型后置+类型推导的时代
Scala
Go
Swift
u name it…

8. expression everywhere

9. var retVal = for{
a <- numList if a != 3; if a < 8
}yield a
for( a <- retVal){
println( "Value of a: " + a );
}
val delimiter = if(defaultDelimiter)’;’ else ‘-’;
Noreturn any more!

10. Combinator
&
Composition

11. Flexible Parameters
But not friendly to Javaers

12. case class

13. How you do it in Java Way?

14. IDEs can help

15. Library can help
Commons Lang
Google Guava
Lombok

16. Let’s do it in Scala Way!

17. tuples

18. static Companion object

19. special `apply` in companion object

20. match
everything and everywhere

21. Pattern Matching Takes Them All

22. extractor object
unapply : Input => Optional[Output]
case class is lucky

23. monad and container objects

24. monad and container objects
you have met Option, right?
But it’s more than Some or None!

25. Monad is too academic,
let’s know it in an easy way
import scala.collection._Go
and Explore…

26. function Rocks

27. Function literals A=>B

28. Partial Applied functions
Are NOT
Partial Functions

29. Partial Applied Functions

30. Partial
Functions

31. Partial Function Tip
scala> val m = Map(1->2, 2->3)
m: scala.collection.immutable.Map[Int,Int] = Map(1 -> 2, 2 -> 3)
scala> m.collect({case (k, v) if k % 2 ==0 => (k,v) })
res7: scala.collection.immutable.Map[Int,Int] = Map(2 -> 3)
scala> m collect {case (k, v) if k % 2 ==0 => (k,v) }
res7: scala.collection.immutable.Map[Int,Int] = Map(2 -> 3)

32. Curried Functions
Caution!
Dark Magic

33. high-order Functions
Try Function
as return value

34. How about Java8?
Both Cool~
as long as you like

35. The
Good
Parts
Of
The
Ecosystem

36. REPL
快速验证你的疑惑和想法

37. The JVMFamily

38. What comes into your mind
when u hear the Java word?

39. Inter-communication
Libraries
Frameworks
Tools

40. SBTmakes build-life easier.

41. Triggered
Execution

42. Wonderful Plugins
SBT Native Packager
Plugin
sbt-assembly
sbt-dependency-graph
you favoured IDEs’ Plugins

43. Concurrency in another way

44. SIP14 Rocks - Futures and Promises
Composable !

45. SIP14 Rocks - Futures and Promises

46. Actor Model
Don’t be silly

47. A Best Practice Of
Message Passing Concurrency

48. Hello Actor
Gravity
u can’t escape

49. IoCWisely

50. Taming Actor
Throttling
Hibernating
Journaling
Clustering

51. web another way

52. URL-Oriented design

53. route - the central hub

54. what a route looks like
[Http Method] [path] [controller method]
GET / controllers.Application.main
POST / controllers.Application.index
# Map static resources from the /public folder to the /assets URL path
GET /assets/*file controllers.Assets.at(path="/public", file)
GET /webjars/*file controllers.WebJarAssets.at(file)

55. Perfect For Web APIScenarios

56. Breakingout of Web Containers

57. make a killing with big data

58. do you know
DryadLINQ
Microsoftdoes NOT always
suck

59. from single framework to family

60. Memory Computing
enhanced with
neat DSL

61. You know Scala Collections well, you
play with Spark well ；）
val textFile = spark.textFile("hdfs://...")
val errors = textFile.filter(line => line.contains("ERROR"))
errors.count()
errors.filter(line => line.contains("MySQL")).count()
errors.filter(line => line.contains("MySQL")).collect()

62. Micro-batching
is not sorealtime

63. ImmediatelyVS. Wait a moment

64. – who said that?!
“Where the fucking awesome
type system of scala?”

65. Scala
wisely

66. 扶墙老师はpuristない

67. Find your own toolbox
not ONLY a
Hammer

68. 海纳百Lang
有容乃大
Java Scala ^_-

69. string interpolation wisely
@see also org.slf4j.helpers.MessageFormatter

70. About Implicit
1. 如果有普遍的共识
和约定的， 可以使用；
2. 否则，不建议使用！

71. Annotation wisely

72. No Perfect Annotation Solution
UglyThing
macross

73. enumeration wisely
or sealed trait?

74. scala
the
endpoints
instead of
the
Dependencies.
Standalone

75. http://afoo.me/posts/2015-03-24-java-scala-project-type-choice-principle.html

76. Questions?

77. over