Started on Scala

scala.html.markdown

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+---
+language: scala
+author: Dominic Bou-Samra
+author_url: http://dbousamra.github.com
+filename: learnscala.scala
+---
+
+Scala is a <insert something nice here>
+
+```scala
+
+///////////////////////////////////////
+// Basic syntax
+///////////////////////////////////////
+
+//  Single line comments start with two forward slashes
+/* 
+Multi line comments look like this.
+*/
+
+// Import packages
+import scala.collection.immutable.List
+// Import all "sub packages"
+import scala.collection.immutable._
+// Import multiple classes in one statement
+import scala.collection.immutable.{List, Map}
+// Rename an import using '=>'
+import scala.collection.immutable{ List => ImmutableList }
+// Import all classes, except some. The following excludes Map and Set:
+import scala.collection.immutable.{Map => _, Set => _, _}
+
+// Your programs entry point is defined in an scala file using an object, with a single method, main:
+object Application {
+  def main(args: Array[String]): Unit = {
+    // stuff goes here.
+  }
+}
+
+// Printing, and forcing a new line on the next print
+println("Hello world!")
+// Printing, without forcing a new line on next print
+print("Hello world")
+
+// Declaring values is done using either var or val
+// val declarations are immutable, whereas var's are mutable. Immutablility is a good thing.
+val x = 10 // x is now 10
+x = 20 // error: reassignment to val
+var x = 10 
+x = 20  // x is now 20
+
+///////////////////////////////////////
+// Types
+///////////////////////////////////////
+
+// Almost all types are objects.
+
+// You have numbers
+3 //3
+
+// Math is as per usual
+1 + 1 // 2
+2 - 1 // 1
+5 * 3 // 15
+6 / 2 // 3
+
+// Boolean values
+true
+false
+
+// Boolean operations
+!true // false
+!false // true
+true == false // false
+10 > 5 // true
+
+// Strings and characters
+"Scala strings are surrounded by double quotes" //
+'a' // A Scala Char
+'Single quote strings don't exist' // Error
+"Strings have the usual Java methods defined on them".length
+"They also have some extra Scala methods.".reverse // See scala.collection.immutable.StringOps
+
+///////////////////////////////////////
+// Basic control constructs
+///////////////////////////////////////
+
+// if statements (else statements are optional)
+if (10 > 5) println("10 is greater than 5")
+// an else
+if (x > 5) println("x is greater than 5")
+else println("No it's not.")
+
+// Iteration
+
+// A while loop
+while (x < 10) {
+  println("x is still less then 10")
+  x += 1
+}
+
+// A do while loop
+do { 
+  println("x is still less then 10"); 
+  x += 1
+} while (x < 10)
+
+// A for loop
+for (x <- 0 until 10) {
+  println(x)
+}
+
+// Any object implementing the map/filter/flatMap methods allows the use of a for loop:
+val aListOfNumbers: List[Int] = List(1, 2, 3)
+for (x <- aListOfNumbers) {
+  println(x)
+}
+
+// Pattern matching (see respective section)
+x match {
+  case 5 => println("x is 5")
+  case 10 => println("x is 10")
+  case _ => println("default case")
+}
+
+///////////////////////////////////////
+// Functions, methods and classes
+///////////////////////////////////////
+
+// Scala has classes
+
+// classname is Dog
+class Dog {
+  //A method called bark, returning a String
+  def bark: String = {
+    // the body of the method
+    "Woof, woof!"
+  }
+}
+
+// They can contain nearly any other construct, including other classes, functions, methods, objects, case classes, traits etc.
+
+///////////////////////////////////////
+// Higher-order functions
+///////////////////////////////////////
+
+// Scala allows methods and functions to return, or take as parameters, other functions or methods.
+
+val add10: Int => Int = _ + 10 // A function taking an Int and returning an Int
+List(1, 2, 3) map add10 // List(11, 12, 13) - add10 is applied to each element
+
+// Anonymous functions can be used instead of named functions:
+List(1, 2, 3) map (x => x + 10)
+
+// And the underscore symbol, can be used if there is just one argument to the anonymous function. It gets bound as the variable
+List(1, 2, 3) map (_ + 10)
+
+TODO // If the anonymous block AND the function you are applying both take one argument, you can even omit the underscore
+List("Dom", "Bob", "Natalia") foreach println
+
+
+// Scala collections have rich higher-order functions defined on them. Some examples:
+
+// The map function takes a function/method, and applies it to each element in the structure
+List(1, 2, 3) map (number => number.toString)
+
+// The filter function takes a predicate (a function from A -> Boolean) and selects all elements which satisfy the predicate
+List(1, 2, 3) filter (_ > 2) // List(3)
+List(
+  Person(name = "Dom", age = 23), 
+  Person(name = "Bob", age = 30)
+).filter(_.age > 25) // List(Person("Bob", 30))
+
+
+// Scala a foreach method defined on certain collections that takes a type returning Unit (a void method)
+aListOfNumbers foreach (x => println(x))
+aListOfNumbers foreach println
+
+