Live coding scala 'the java of the future'

Live Coding 'the Java of the future’

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

Core ingredients of Scala

1.7

Java

Options
Our first sip of
Classes

Tuples

Traits

Implicits

Loops

A single ride with many loops

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"

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);"
"
"
"
Scala

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

Java8 will have internal iteration with Lambda expressions

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

Scala

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

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’"

Scala

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

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<>());"

Scala

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

Delivery date

Java8
"
" 2013 !
in JDK 8!

Scala

"
"
since 2010 !
in JDK 1.5, 1.6, 1.7 !
"
With an impressive track record of many mission
critical applications by now ..."

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'

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