Dive into Scala

<<If you know how to write your first program using scala go to Deep dive into Scala >>

You know java, ruby, groovy, python - unlearn those momentarily if you need to learn scala (for that matter any new paradigm). Though smalltalk and haskell knowledge may help. I learned a little bit of haskell to understand what the functional world of languages looks like. Any way scala is an awesome language but without unlearning mainstream languages it may appear seemingly difficult. Lets see one example - a bad old HelloWorld. Before that just download scala from http://www.scala-lang.org/downloads. Pick up appropriate package for your OS, install it, don't forget to make it available in your system path - you know how easy it is; I am not going to explain it here. Now lets say your done - commands scala, scalac are in your system path. Issue scala command from your terminal and you can see the scala shell as below. 

scala>

This is scala shell. Lets write a program directly there. 

scala> print("my name")

and it will display 

my name 

We have got the first dose of our scala - lets now see a real program

scala> object HelloWorld { | def main(args: Array[String]) { | println("Hello World!!!") | } | }

write the above code as it is written here with maintaining the lines from scala prompt. At the end when you press your last "Return/Enter" you see

defined module HelloWorld

And then run it like this from scala prompt

scala> HelloWorld.main(null)

And you will see

HelloWorld!!!

Cool... we saw how to write the first scala program. The difference so far with java or other languages that we defined object directly. Don't worry we can define class too. We will see that next.

scala> class HelloWorld { | def main(args: Array[String]) { | println("HelloWorld!!!") | } | } And you see the message
defined class HelloWorld

Lets run it now
scala>var hw = new HelloWorld
scala>hw.main(null) You see

HelloWorld!!!

on the display

Hello world program done. We should dive deep into the theories of scala. The values it brings, the added advantages over java and other mainstream and contemporary languages. The notion of functional language, the traits and mix-ins, the Actor and concurrency, the compact syntaxes etc. Tune in to my next post - coming in few hours.

One thing - obvious - forgot to mention. You can write the above to code examples in file. If the file name is HelloWorld.scala you can compile it from your terminal shell (not scala shell) using scalac HelloWorld.scala

and then run it from terminal shell like this scala -classpath . HelloWorld

Next read Deep dive into Scala