Öredev 2010 Dag 1 (tisdag) anteckningar

Koans, Katas, Oh my by Cory Foy

Corys slides and links can be found here: http://blog.coryfoy.com/2010/11/koans-and-katas-oh-my-slides-and-links-from-my-%C3%B8redev-2010-session/

Practice outside production is essential

Write dreyfus number 1-5 on head of others in conversation

Shu Ha Ri

Koans is a mindset, the actual excercises are katas.

Katas: You know solution, practice solving them

Code Kata origin: Dave Thomas

Katacasts

KataFizzBuzz

http://codingdojo.org/cgi-bin/wiki.pl?KataFizzBuzz

TDD as you meant it (gojko.net)

Only refactor out production code

Code retreat - C0d3r3tr3at

Game Of Life

How do we try out stuff otherwise? We introduce in in our production code! Is that good?

Cory Haynes – Has done a lot of Javascript testing lately.

Scala Thinking by Ted Neward

Functional

• Order Does Not Matter à No notion of sequence like

·        i=1;

·        i =i+2;

• There is no shared state à always same return from function – no side effects.
• But: Sometimes order matter (fly before explodes)
• Scala says: There’s goodness in both functional and OO world.

What the outcome of combo of F and OO is not yet known, nobody knows!

Scala is impure FL, allows

-         functions as first-class values

-         strongly typed, type-inferenced

-         immutable values

-         expressions-not-statements

-         typles, lists                                        

-         recursion

-         pattern-matching

-         currying, partial-application of functions

lambda calculus

f(x,y) = x + y

f(x,y,op) = x (op) y

add (x, y) = x + y

inc = add 1                          (returns first class value function that takes one value)

Function that takes more than 2 parameters are too long – compare to Bob J

Currying à Pipelining

Val convertToInt = { x:String => x.toInt }

Val doubleIt = { x:Int => x * 2 }

Val sqrtIt = { x:Double => Mat.sqrt(x) }

Val pipeline = convertToInt andThen doubleIt andThen int2double andThen sqrtIt

RUN:

Scalac person.scala

Java –classpath ;. App

Javap Person                       (Shows java-code)

object App {

Using eclipse? ScalaIDE, http://www.scala-ide.org/

Unit testing? Yepp, but maybe Java TDD? Make unit testing first compile scala? Would be cool to integrate!

Using from Java?

Problems

http://aperiodic.net/phil/scala/s-99

http://langref.org/scala/solved

lift framework

Tomorrow: Go to Java Bytecode!!!

Anything is better than java.

Why use scala: Unless you want to write tomorrows legacy code today.