Live coding scala 'the java of the future'

Urs Peter 19:45 uur - Zaal Zand (boven)

Live Coding

'the Java of the future’

Core ingredients of Scala

Java

1.7

Who uses Scala?

Scala Dev environment

Classes

Options Our first sip of

Traits

Implicits

Tuples

Loops

A single ride with many loops

Pattern Matching

The future is bright, the future is fun -ctional

Scala Collections

The beginning of a beautiful friendship

Google Code Jam Exercise Problem The aim of this task is to translate a language into a new language called Googlerese. To translate we take any message and replace each English le<er with another English le<er. This mapping is one-‐to-‐one and onto, which means that the same input le<er always gets replaced with the same output le<er, and different input le<ers always get replaced with different output le<ers. A le<er may be replaced by itself. Spaces are leC as-‐is. For example (and here is a hint!), the translaIon algorithm includes the following three mappings: 'a' -‐> 'y', 'o' -‐> 'e', and 'z' -‐> 'q'. This means that "a zoo" will become "y qee". Sample Input/Output Input: Case #1: ejp mysljylc kd kxveddknmc re jsicpdrysi

Case #2: rbcpc ypc rtcsra dkh wyfrepkym veddknkmkrkcd Case #3: de kr kd eoya kw aej tysr re ujdr lkgc jv"

Output: Case #1: our language is impossible to understand

Case #2: there are twenty six factorial possibilities Case #3: so it is okay if you want to just give up"

Lets go parallel

(Back to) The future of Java

Java8 will have Lambda Expressions Java

root.listFiles((File f) -> f.isDirectory());""//even with type inference"root.listFiles(f -> f.isDirectory());""//... and shorthand notation"root.listFiles(File::isDirectory);""""

root.listFiles(f:File => f.isDirectory)""root.listFiles(f => f.isDirectory)""root.listFiles(_.isDirectory)"

Scala

Java8 will have internal iteration with Lambda expressions Java

double highestScore ="" students.filter(Student s -> s.getGradYear() == 2011)"" " .map(Student s -> s.getScore())"" " .max();"

""

val highestScore = ""studens.filter(s:Student => s.gradYear == 2011)"" ".map(s:Student => s.score)"" ".max"

Scala

Java8 will have default implementations for interfaces (virtual extension methods) Java ""

""interface List<T> … {"

"// existing methods, plus""void sort(Comparator<? super T> cmp) "default { "" "Collections.sort(this, cmp); }""}"

//however: no fields, no self types, "//... And therefore ‘no multiple inheritance without the issues’"

Traits ..."//with fields, self types"//... And therefore: ‘multiple inheritance without the issues’"

Scala

Java8 will have support for parallel Collections Java ""

"Set<Album> favs =" albums.parallel()"

" .filter(a -> a.tracks.anyMatch(t -> (t.rating >= 4)))"" .into(new ConcurrentHashSet<>());"

val favs = " albums.par! .filter(a => a.tracks.exists(t => t.rating >= 4)" .toSet" "

Scala

Delivery date Java8 ""

2013 !in JDK 8!

"" "With an impressive track record of many mission critical applications by now ..."

since 2010 !in JDK 1.5, 1.6, 1.7 !

Scala

My Advice:

and enjoy:

def ask(question: Any) = question match {! case "?" => "answer for ?"! case "???" => "answer for ???"! case _ => "42"! }"

Live coding scala 'the java of the future'

Technology

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