small changes to basics

tutorials/tour/_posts/2017-02-13-basics.md

@@ -26,7 +26,9 @@ This is an easy, zero-setup way to experiment with pieces of Scala code.
 ## Expressions
 
 Expressions are computable statements.
-
+```
+1 + 1
+```
 You can output results of expressions using `println`.
 
 ```tut
@@ -61,6 +63,8 @@ Types of values can be inferred, but you can also explicitly state the type, lik
 val x: Int = 1 + 1
 ```
 
+Notice how the type declaration `Int` comes after the identifier `x`. You also need a `:`.  
+
 ### Variables
 
 Variables are like values, except you can re-assign them. You can define a variable with the `var` keyword.
@@ -77,7 +81,8 @@ As with values, you can explicitly state the type if you want:
 var x: Int = 1 + 1
 ```
 
-### Blocks
+
+## Blocks
 
 You can combine expressions by surrounding them with `{}`. We call this a block.
 
@@ -94,7 +99,7 @@ println({
 
 Functions are expressions that take parameters.
 
-You can define a function that returns a given integer plus one:
+You can define an anonymous function (i.e. no name) that returns a given integer plus one:
 
 ```tut
 (x: Int) => x + 1
@@ -123,7 +128,7 @@ val getTheAnswer = () => 42
 println(getTheAnswer()) // 42
 ```
 
-We will cover functions in depth [later](anonymous-function-syntax.md).
+We will cover functions in depth [later](anonymous-function-syntax.html).
 
 ## Methods
 
@@ -136,13 +141,7 @@ def add(x: Int, y: Int): Int = x + y
 println(add(1, 2)) // 3
 ```
 
-Methods cannot be named with the `val` or `var` keywords.
-
-```tut:nofail
-def add(x: Int, y: Int): Int = x + y
-val add2 = add // This does not compile.
-var add3 = add // This does not compile either.
-```
+Notice how the return type is declared _after_ the parameter list and a colon `: Int`.
 
 Methods can take multiple parameter lists.
 
@@ -160,6 +159,15 @@ println("Hello, " + name + "!")
 
 There are some other differences, but for now, you can think of them as something similar to functions.
 
+Methods can have multi-line expressions as well.
+```tut
+def getSquareString(input: Double): String = {
+  val square = input * input
+  square.toString
+}
+```
+The last expression in the body is the method's return value. (Scala does have a `return` keyword, but it's rarely used.)
+
 ## Classes
 
 You can define classes with the `class` keyword followed by its name and constructor parameters.
@@ -170,6 +178,7 @@ class Greeter(prefix: String, suffix: String) {
     println(prefix + name + suffix)
 }
 ```
+The return type of the method `greet` is `Unit`, which says there's nothing meaningful to return. It's used similarly to `void` in Java and C. (A difference is that because every Scala expression must have some value, there is actually a singleton value of type Unit, written (). It carries no information.)
 
 You can make an instance of a class with the `new` keyword.
 
@@ -178,7 +187,7 @@ val greeter = new Greeter("Hello, ", "!")
 greeter.greet("Scala developer") // Hello, Scala developer!
 ```
 
-We will cover classes in depth [later](classes.md).
+We will cover classes in depth [later](classes.html).
 
 ## Case Classes
 
@@ -214,7 +223,7 @@ if (point == yetAnotherPoint) {
 // Point(1,2) and Point(2,2) are different.
 ```
 
-There is a lot more to case classes that we'd like to introduce, and we are convinced you will fall in love with them! We will cover them in depth [later](case-classes.md).
+There is a lot more to case classes that we'd like to introduce, and we are convinced you will fall in love with them! We will cover them in depth [later](case-classes.html).
 
 ## Objects
 
@@ -241,7 +250,7 @@ val newerId: Int = IdFactory.create()
 println(newerId) // 2
 ```
 
-We will cover objects in depth [later](singleton-objects.md).
+We will cover objects in depth [later](singleton-objects.html).
 
 ## Traits
 
@@ -284,7 +293,7 @@ customGreeter.greet("Scala developer") // How are you, Scala developer?
 
 Here, `DefaultGreeter` extends only a single trait, but it could extend multiple traits.
 
-We will cover traits in depth [later](traits.md).
+We will cover traits in depth [later](traits.html).
 
 ## Main Method