//typical function declaration
fun sum(a: Int, b: Int) : Int {
return a+b
}
//function expression
fun sum(a: Int, b: Int) = a+b
//default parameters
fun payClerck(pay: Double , tip: Double = 1.0) : Double {
return pay+ tip
}
//calling
payClerck(10.)
payClerck(10., 2.)
//using named parameters it is possible to change their
// order when calling the function
payClerck(tip = 1., pay = 2.0)
In kotlin functions are first class citizens:
A first-class citizen […] is an entity which supports all the operations generally available to other entities. These operations typically include being passed as an argument, returned from a function, modified, and assigned to a variable. (Wikipedia)
Functions do not need to be declared inside a class.
Functions can be declared locally
miniguide 