README

Semicolon optional unless multiple statements on same line

Main

object session extends App {
    println("Hello world")
}

object session {
    def main {
        println("Hello world")
    }
}

Basic Defining Blocks

• Call by value: evaluates the function arguments before calling the function

• Call by name: evaluates the function first, and then evaluates the arguments if need be

def example = 2      // evaluated when called
val example = 2      // evaluated immediately and immutable
var exmaple = 2 //variable and immediate
lazy val example = 2 // evaluated once when needed

def loop = loop //won't loop forever at this line
val loop = loop //will loop forever at this line

def square(x: Double)    // call by value
def square(x: => Double) // call by name
def myFct(bindings: Int*) = { ... } // bindings is a sequence of int, containing a varying # of arguments

Expressions

the building block of scala

Blocks {} are an expression that returns the last expression's value. so can be stored in variables returned by functions and be parameters

var y = 2        //variable    
val x = 1        //immutable

Basic Types

"" - strings

'' - chars

Any is base type of all types and defines:

• == - calls Java equals

• hashCode

• toString

AnyRef is basetype of all reference types and AnyVal is base type of all primitative types

Nothing is subtype of every type(so it can be passed/returned), yet no value has type nothing. Used when fts fail to return anything by ending abnormally(errs) or element type of empty collections(Set[Nothing]).

The type of null is Null i.e val x = null. null is subtype of AnyVal

Useful b/c can write ft like if x 1 else false which will be type ddddddAnyVal