What do we mean by abstractions? Why are they important? To understand this, we will compare two approaches. First, the "go to the wall and pull at one of the wooden panels fitted into the rectangular hole" approach versus the "open the door, please" approach.
A door is an abstraction. We really don't care whether it is made of wood or some other material, or what type of a lock it has, or any other details. The details are important, but not always. If we worry about the details always, we would quickly get bogged down, and all the communication would effectively come to a halt.
A table is an abstraction, so is a chair, and so is a house. I hope you get the drift. We want to be selectively ignorant of the details at times, and selective ignorance is abstraction.
Now, you may ask why does it matter to us programmers? The reason is that it gets things done in a compact manner.
For example, let's look at the following Scala code, which is used to count the frequency of characters in a string:
scala> "hello world".toList.filter(_.isLetter).groupBy(x => x).map { y => | y._1 -> y._2.size | } res1: scala.collection.immutable.Map[Char,Int] = Map(e -> 1, l -> 3, h -> 1, r -> 1, w -> 1, o -> 2, d -> 1)
Isn't it compact?
On the Urban Dictionary website, http://www.urbandictionary.com/define.php?term=cutie, the term "cutie" is defined as compact beauty—the kind you just want to put in your pocket and keep beside you forever.
I was bowled over when I first saw it all. It is concise, short, packs a punch, and is elegant. The Type Less Do More philosophy. Gets a lot done with less...
Note
To run the code snippet, fire up the Scala REPL. This looks a lot like a command console, a prompt waiting for you to key in Scala code. In a command terminal, typing just Scala fires up the REPL:
~> scala
It will give the following output:
Welcome to Scala version 2.11.7 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_25).
You can type in expressions to have them evaluated and type help for more information. Let's try the following simple one line commands:
scala> 1 + 1 res2: Int = 2 scala> "hello".length res4: Int = 5
For me, Scala brought the thrill back to programming... You can do a great deal by writing a few lines of code—less is more...
Scala gives you many tools, so the code is abstract and reusable...