Merge branch 'master' of https://github.com/adambard/learnxinyminutes-docs

3 files changed, 419 insertions, 250 deletions

diff --git a/Visual Basic b/Visual Basic
deleted file mode 100644
index 73430633..00000000
--- a/Visual Basic
+++ /dev/null
@@ -1,248 +0,0 @@
----
-language: Visual Basic Console Application
-contributors:
-    - ["Brian Martin", "http://brianmartin.biz"]
-filename: learnvisualbasic.vb
-
-Module Module1
-
-    Sub Main()
-        'A Quick Overview of Visual Basic Console Applications before we dive in to the deep end.
-        'Apostrophe starts comments.
-        'To Navigate this tutorial within the Visual Basic Complier, I've put together a navigation system.
-        'This navigation system is explained however as we go deeper into this tutorial, you'll understand what it all means.
-        Console.Title = ("Learn X in Y Minutes")
-        Console.WriteLine("NAVIGATION") 'Display 
-        Console.WriteLine("")
-        Console.ForegroundColor = ConsoleColor.Green
-        Console.WriteLine("1. Hello World Output")
-        Console.WriteLine("2. Hello World Input")
-        Console.WriteLine("3. Calculating Whole Numbers")
-        Console.WriteLine("4. Calculating Decimal Numbers")
-        Console.WriteLine("5. Working Calculator")
-        Console.WriteLine("6. Using Do While Loops")
-        Console.WriteLine("7. Using For While Loops")
-        Console.WriteLine("8. Conditional Statements")
-        Console.WriteLine("9. Select A Drink")
-        Console.WriteLine("50. About")
-        Console.WriteLine("Please Choose A Number From The Above List")
-        Dim selection As String = Console.ReadLine
-        Select Case selection
-            Case "1" 'HelloWorld Output
-                Console.Clear() 'Clears the application and opens the private sub
-                HelloWorldOutput() 'Name Private Sub, Opens Private Sub
-            Case "2" 'Hello Input
-                Console.Clear()
-                HelloWorldInput()
-            Case "3" 'Calculating Whole Numbers 
-                Console.Clear()
-                CalculatingWholeNumbers()
-            Case "4" 'Calculting Decimal Numbers 
-                Console.Clear()
-                CalculatingDecimalNumbers()
-            Case "5" 'Working Calcculator 
-                Console.Clear()
-                WorkingCalculator()
-            Case "6" 'Using Do While Loops
-                Console.Clear()
-                UsingDoWhileLoops()
-            Case "7" 'Using For While Loops
-                Console.Clear()
-                UsingForLoops()
-            Case "8" 'Conditional Statements
-                Console.Clear()
-                ConditionalStatement()
-            Case "9" 'If/Else Statement
-                Console.Clear()
-                IfElseStatement() 'Select a drink
-            Case "50" 'About msg box
-                Console.Clear()
-                Console.Title = ("Learn X in Y Minutes :: About")
-                MsgBox("Learn X in Y Minutes is a creation of Adam Bard (@adambard) This particular program tutorial is by Brian Martin (@BrianMartinn")
-                Console.Clear()
-                Main()
-                Console.ReadLine()
-
-        End Select
-    End Sub
-
-    'One - I'm using numbers to help with the above navigation when I come back later to build it.
-    Private Sub HelloWorldOutput()  'We use private subs to seperate different sections of the program. 
-        Console.Title = "Hello World Ouput | Learn X in Y Minutes" 'Title of Console Application
-        'Use Console.Write("") or Console.WriteLine("") to print outputs.
-        'Followed by Console.Read() alternatively Console.Readline()
-        'Console.ReadLine() prints the output to the console.
-        Console.WriteLine("Hello World")
-        Console.ReadLine()
-    End Sub
-    'Two
-    Private Sub HelloWorldInput() 'We use private subs to seperate different sections of the program. 
-        Console.Title = "Hello World YourName | Learn X in Y Minutes" 'Title of Console Application
-        'Variables
-        'Data entered by a user needs to be stored.
-        'Variables also start with a Dim and end with an As VariableType.
-        Dim username As String 'In this tutorial, we want to know what your name, and make the program respond to what is said.
-        'We use string as string is a text based variable.
-        Console.WriteLine("Hello, What is your name? ") 'Ask the user their name.
-        username = Console.ReadLine() 'Stores the users name.
-        Console.WriteLine("Hello " + username) 'Output is Hello 'Their name'
-        Console.ReadLine() 'Outsputs the above.
-        'The above will ask you a question followed by printing your answer.
-        'Other variables include Integer and we use Integer for whole numbers.
-    End Sub
-    'Three
-    Private Sub CalculatingWholeNumbers() 'We use private subs to seperate different sections of the program. 
-        Console.Title = "Calculating Whole Numbers | Learn X in Y Minutes" 'Title of Console Application
-        Console.Write("First number: ") 'Enter a whole number, 1, 2, 50, 104 ect
-        Dim a As Integer = Console.ReadLine()
-        Console.Write("Second number: ") 'Enter second whole number.
-        Dim b As Integer = Console.ReadLine()
-        Dim c As Integer = a + b
-        Console.WriteLine(c)
-        Console.ReadLine()
-        'The above is a simple calculator
-    End Sub
-    'Four
-    Private Sub CalculatingDecimalNumbers()
-        Console.Title = "Calculating with Double | Learn X in Y Minutes" 'Title of Console Application
-        'Of course we would like to be able to add up decimals.
-        'Therefore we could change the above from Integer to Double.
-        Console.Write("First number: ") 'Enter a whole number, 1.2, 2.4, 50.1, 104.9 ect
-        Dim a As Double = Console.ReadLine
-        Console.Write("Second number: ") 'Enter second whole number.
-        Dim b As Double = Console.ReadLine
-        Dim c As Double = a + b
-        Console.WriteLine(c)
-        Console.ReadLine()
-        'Therefore the above program can add up 1.1 - 2.2
-    End Sub
-    'Five
-    Private Sub WorkingCalculator()
-        Console.Title = "The Working Calculator| Learn X in Y Minutes" 'Title of Console Application
-        'However if you'd like the calculator to subtract, divide, multiple and add up.
-        'Copy and paste the above again.
-        Console.Write("First number: ") 'Enter a whole number, 1.2, 2.4, 50.1, 104.9 ect
-        Dim a As Double = Console.ReadLine
-        Console.Write("Second number: ") 'Enter second whole number.
-        Dim b As Integer = Console.ReadLine
-        Dim c As Integer = a + b
-        Dim d As Integer = a * b
-        Dim e As Integer = a - b
-        Dim f As Integer = a / b
-        'By adding the below lines we are able to calculate the subtract, multply as well as divide the a and b values
-        Console.Write(a.ToString() + " + " + b.ToString())
-        Console.WriteLine(" = " + c.ToString.PadLeft(3)) 'We want to pad the answers to the left by 3 spaces.
-        Console.Write(a.ToString() + " * " + b.ToString())
-        Console.WriteLine(" = " + d.ToString.PadLeft(3)) 'We want to pad the answers to the left by 3 spaces.
-        Console.Write(a.ToString() + " - " + b.ToString())
-        Console.WriteLine(" = " + e.ToString.PadLeft(3)) 'We want to pad the answers to the left by 3 spaces.
-        Console.Write(a.ToString() + " / " + b.ToString())
-        Console.WriteLine(" = " + e.ToString.PadLeft(3)) 'We want to pad the answers to the left by 3 spaces.
-        Console.ReadLine()
-
-    End Sub
-    'Six
-    Private Sub UsingDoWhileLoops()
-        'Just as the previous private sub
-        'This Time We Ask If The User Wishes To Continue (Yes or No?)
-        'We're using Do While Loop as we're unsure if the user wants to use the program more than once.
-        Console.Title = "UsingDoWhileLoops | Learn X in Y Minutes"
-        Dim answer As String 'We use the variable "String" as the answer is text
-        Do 'We start the program with 
-            Console.Write("First number: ")
-            Dim a As Double = Console.ReadLine
-            Console.Write("Second number: ")
-            Dim b As Integer = Console.ReadLine
-            Dim c As Integer = a + b
-            Dim d As Integer = a * b
-            Dim e As Integer = a - b
-            Dim f As Integer = a / b
-
-            Console.Write(a.ToString() + " + " + b.ToString())
-            Console.WriteLine(" = " + c.ToString.PadLeft(3))
-            Console.Write(a.ToString() + " * " + b.ToString())
-            Console.WriteLine(" = " + d.ToString.PadLeft(3))
-            Console.Write(a.ToString() + " - " + b.ToString())
-            Console.WriteLine(" = " + e.ToString.PadLeft(3))
-            Console.Write(a.ToString() + " / " + b.ToString())
-            Console.WriteLine(" = " + e.ToString.PadLeft(3))
-            Console.ReadLine()
-            'Ask the question, does the user wish to continue? Unfortunately it is case sensitive. 
-            Console.Write("Would you like to continue? (yes / no)")
-            answer = Console.ReadLine 'The program grabs the variable and prints and starts again.
-        Loop While answer = "yes" 'The command for the variable to work would be in this case "yes"
-
-    End Sub
-    'Seven
-    Private Sub UsingForLoops()
-        'Sometimes the program only needs to run once.
-        'In this program we'll be counting down from 10.
-
-        Console.Title = "Using For Loops | Learn X in Y Minutes"
-        For i As Integer = 10 To 0 Step -1 'Declare Vairable and what number it should count down in Step -1, Step -2, Step -3 ect. 
-            Console.WriteLine(i.ToString) 'Print the value of the counter variable
-        Next i 'Calculate new value
-        Console.WriteLine("Start") 'Lets start the program baby!!
-        Console.ReadLine() 'POW!! - Perhaps I got a little excited then :)
-    End Sub
-    'Eight
-    Private Sub ConditionalStatement()
-        Console.Title = "Conditional Statements | Learn X in Y Minutes"
-        Dim userName As String = Console.ReadLine
-        Console.WriteLine("Hello, What is your name? ") 'Ask the user their name.
-        userName = Console.ReadLine() 'Stores the users name.
-        If userName = "Adam" Then 'Hey, if Adam uses this program, kudos where kudos is due, right?
-            Console.WriteLine("Hello Adam")
-            Console.WriteLine("Thanks for creating the useful tutorial site www.learnxinyminutes.com!")
-            Console.ReadLine()
-        Else
-            Console.WriteLine("Hello " + userName) 'prints the username of the user 
-            Console.WriteLine("Hope all is well have you checked out www.learnxinyminutes.com") 'Prints a message to the user
-            Console.ReadLine() 'Ends and prints the above statement.
-        End If
-    End Sub
-    'Nine
-    Private Sub IfElseStatement()
-    Console.Title = "If / Else Statement | Learn X in Y Minutes"
-        'Sometimes its important to consider more than two alternatives. Sometimes there are a good few others.
-        'When this is the case, more than one if statement would be required.
-        'An if statement is great for vending machines. Where the user enters a code.
-        'A1, A2, A3, ect to select an item.
-        'All choices can be combined into a single if statement.
-
-        Dim selection As String = Console.ReadLine 'Value for selection
-            Console.WriteLine("A1. for 7Up")
-            Console.WriteLine("A2. for Fanta")
-            Console.WriteLine("A3. for Dr. Pepper")
-            Console.WriteLine("A4. for Diet Coke")
-            Console.ReadLine()
-            If selection = "A1" Then
-                Console.WriteLine("7up")
-                Console.ReadLine()
-            ElseIf selection = "A2" Then
-                Console.WriteLine("fanta")
-                Console.ReadLine()
-            ElseIf selection = "A3" Then
-                Console.WriteLine("dr. pepper")
-                Console.ReadLine()
-            ElseIf selection = "A4" Then
-                Console.WriteLine("diet coke")
-                Console.ReadLine()
-            Else
-                Console.WriteLine("Please select a product")
-                Console.ReadLine()
-            End If
-
-    End Sub
-
-End Module
-
-
-```
-## References
-
-I learnt Visual Basic in the console application. It allowed me to understand the principles of computer programming to go on to learn other programming languages easily. 
-
-I created a more indepth <a href="http://www.vbbootcamp.co.uk/" Title="Visual Basic Tutorial">Visual Basic tutorial</a> for those who would like to learn more. 
-
-The entire syntax is valid. Copy the and paste in to the Visual Basic complier and run (F5) the program. 
diff --git a/php.html.markdown b/php.html.markdown
index 5f5a4b54..ce228870 100644
--- a/php.html.markdown
+++ b/php.html.markdown
@@ -9,7 +9,7 @@ filename: learnphp.php
 This document describes PHP 5+.
 
 ```php
-<?php // PHP code must be enclosed with <?php ?> tags
+<?php // PHP code must be enclosed with <?php tags
 
 // If your php file only contains PHP code, it is best practise
 // to omit the php closing tag.
@@ -31,7 +31,8 @@ echo "World\n"; // Prints "World" with a line break
 // (all statements must end with a semicolon)
 
 // Anything outside <?php tags is echoed automatically
-?>Hello World Again!
+?>
+Hello World Again!
 <?php
 
 
diff --git a/scala.html.markdown b/scala.html.markdown
new file mode 100644
index 00000000..fef09404
--- /dev/null
+++ b/scala.html.markdown
@@ -0,0 +1,416 @@
+---
+language: Scala
+filename: learnscala.scala
+contributors:
+    - ["George Petrov", "http://github.com/petrovg"]
+    - ["Dominic Bou-Samra", "http://dbousamra.github.com"]
+filename: learn.scala
+---
+
+Scala - the scalable language
+
+```cpp
+
+/*
+  Set yourself up:
+
+  1) Download Scala - http://www.scala-lang.org/downloads
+  2) unzip/untar in your favourite location and put the bin subdir on the path
+  3) Start a scala REPL by typing scala. You should see the prompt:
+
+  scala>
+
+  This is the so called REPL. You can run commands in the REPL. Let's do just
+  that:
+*/
+
+println(10) // prints the integer 10
+
+println("Boo!") // printlns the string Boo!
+
+
+// Some basics
+
+// 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
+
+//  Single line comments start with two forward slashes
+/* 
+Multi line comments look like this.
+*/
+
+// Boolean values
+true
+false
+
+// Boolean operations
+!true // false
+!false // true
+true == false // false
+10 > 5 // true
+
+// Math is as per usual
+1 + 1 // 2
+2 - 1 // 1
+5 * 3 // 15
+6 / 2 // 3
+
+
+// Evaluating a command in the REPL gives you the type and value of the result
+
+1 + 7
+
+/* The above line results in:
+
+  scala> 1 + 7
+  res29: Int = 8
+
+  This means the result of evaluating 1 + 7 is an object of type Int with a
+  value of 8
+
+  1+7 will give you the same result
+*/
+
+
+// Everything is an object, including a function. Type these in the REPL:
+
+7 // results in res30: Int = 7 (res30 is just a generated var name for the result)
+
+// The next line gives you a function that takes an Int and returns it squared
+(x:Int) => x * x    
+
+// You can assign this function to an identifier, like this:
+val sq = (x:Int) => x * x
+
+/* The above says this
+   
+   sq: Int => Int = <function1>	
+
+   Which means that this time we gave an explicit name to the value - sq is a
+   function that take an Int and returns Int.
+
+   sq can be executed as follows:
+*/
+
+sq(10)   // Gives you this: res33: Int = 100.
+
+// 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)
+
+// 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
+
+
+
+// Data structures
+
+val a = Array(1, 2, 3, 5, 8, 13)
+a(0)
+a(3)
+a(21)    // Throws an exception
+
+val m = Map("fork" -> "tenedor", "spoon" -> "cuchara", "knife" -> "cuchillo")
+m("fork")
+m("spoon")
+m("bottle")       // Throws an exception
+
+val safeM = m.withDefaultValue("no lo se")
+safeM("bottle")
+
+val s = Set(1, 3, 7)
+s(0)
+s(1)
+
+/* Look up the documentation of map here - 
+ * http://www.scala-lang.org/api/current/index.html#scala.collection.immutable.Map 
+ * and make sure you can read it
+ */
+
+
+// Tuples
+
+(1, 2)
+
+(4, 3, 2)
+
+(1, 2, "three")
+
+(a, 2, "three")
+
+// Why have this?
+val divideInts = (x:Int, y:Int) => (x / y, x % y)
+
+divideInts(10,3) // The function divideInts gives you the result and the remainder
+
+// To access the elements of a tuple, use _._n where n is the 1-based index of
+// the element
+val d = divideInts(10,3)
+
+d._1
+
+d._2
+
+
+
+// Combinators
+
+s.map(sq)
+
+val sSquared = s. map(sq)
+
+sSquared.filter(_ < 10)
+
+sSquared.reduce (_+_)
+
+// 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
+
+
+
+
+// For comprehensions
+
+for { n <- s } yield sq(n)
+
+val nSquared2 = for { n <- s } yield sq(n)
+
+for { n <- nSquared2 if n < 10 } yield n
+
+for { n <- s; nSquared = n * n if nSquared < 10} yield nSquared
+
+/* NB Those were not for loops. The semantics of a for loop is 'repeat', whereas
+   a for-comprehension defines a relationship between two sets of data. */
+
+
+
+// Loops and iteration
+
+1 to 5
+val r = 1 to 5
+r.foreach( println )
+
+r foreach println     
+// NB: Scala is quite lenient when it comes to dots and brackets - study the
+// rules separately. This helps write DSLs and APIs that read like English
+
+(5 to 1 by -1) foreach ( println )
+
+// A while loops
+var i = 0
+while (i < 10) {  println("i " + i); i+=1  }
+
+while (i < 10) {  println("i " + i); i+=1  }   // Yes, again. What happened? Why?
+
+i    // Show the value of i. Note that while is a loop in the classical sense -
+     // it executes sequentially while changing the loop variable. while is very
+     // fast, faster that Java // loops, but using the combinators and
+     // comprehensions above is easier to understand and parallelize
+
+// A do while loop
+do {
+  println("x is still less then 10"); 
+  x += 1
+} while (x < 10)
+
+// Tail recursion is an idiomatic way of doing recurring things in Scala.
+// Recursive functions need an explicit return type, the compiler can't infer it.
+// Here it's Unit.
+def showNumbersInRange(a:Int, b:Int):Unit = {
+  print(a)
+  if (a < b)
+    showNumbersInRange(a + 1, b)
+}
+
+
+
+// Conditionals
+
+val x = 10
+
+if (x == 1) println("yeah")
+if (x == 10) println("yeah")
+if (x == 11) println("yeah")
+if (x == 11) println ("yeah") else println("nay")
+
+println(if (x == 10) "yeah" else "nope")
+val text = if (x == 10) "yeah" else "nope"
+
+var i = 0
+while (i < 10) { println("i " + i); i+=1  }
+
+
+
+// Object oriented features
+
+// Classname is Dog
+class Dog {
+  //A method called bark, returning a String
+  def bark: String = {
+    // the body of the method
+    "Woof, woof!"
+  }
+}
+
+// Classes can contain nearly any other construct, including other classes,
+// functions, methods, objects, case classes, traits etc.
+
+
+
+// Case classes
+
+case class Person(name:String, phoneNumber:String)
+
+Person("George", "1234") == Person("Kate", "1236")
+
+
+
+
+// Pattern matching
+
+val me = Person("George", "1234")
+
+me match { case Person(name, number) => {
+            "We matched someone : " + name + ", phone : " + number }}
+
+me match { case Person(name, number) => "Match : " + name; case _ => "Hm..." }
+
+me match { case Person("George", number) => "Match"; case _ => "Hm..." }
+
+me match { case Person("Kate", number) => "Match"; case _ => "Hm..." }
+
+me match { case Person("Kate", _) => "Girl"; case Person("George", _) => "Boy" }
+
+val kate = Person("Kate", "1234")
+
+kate match { case Person("Kate", _) => "Girl"; case Person("George", _) => "Boy" }
+
+
+
+// Regular expressions
+
+val email = "(.*)@(.*)".r  // Invoking r on String makes it a Regex
+
+val email(user, domain) = "henry@zkpr.com"
+
+"mrbean@pyahoo.com" match {
+  case email(name, domain) => "I know your name, " + name
+}
+
+
+
+// Strings
+
+"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
+
+// Seealso:  scala.collection.immutable.StringOps
+
+println("ABCDEF".length)
+println("ABCDEF".substring(2, 6))
+println("ABCDEF".replace("C", "3"))
+
+val n = 45
+println(s"We have $n apples")
+
+val a = Array(11, 9, 6)
+println(s"My second daughter is ${a(2-1)} years old")
+
+// Some characters need to be 'escaped', e.g. a double quote inside a string:
+val a = "They stood outside the \"Rose and Crown\""
+
+// Triple double-quotes let strings span multiple rows and contain quotes
+
+val html = """<form id="daform">
+                <p>Press belo', Joe</p>
+             |  <input type="submit">
+              </form>"""
+
+
+
+// Application structure and organization
+
+// Importing things
+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.
+  }
+}
+
+// Files can contain multiple classes and objects. Compile with scalac
+
+
+
+
+// Input and output
+
+// To read a file line by line
+import scala.io.Source
+for(line <- Source.fromPath("myfile.txt").getLines())
+  println(line)
+
+// To write a file use Java's PrintWriter
+
+
+```
+
+## Further resources
+
+[Scala for the impatient](http://horstmann.com/scala/)
+
+[Twitter Scala school(http://twitter.github.io/scala_school/)
+
+[The scala documentation]
+
+Join the [Scala user group](https://groups.google.com/forum/#!forum/scala-user)
+