scala - What are named and default arguments? -

i heard scala contains feature called named , default arguments don't know such parameters or how use them.

can explain usage?

some special functions call type in scala

named arguments:

named arguments allow pass arguments function in different order.for example:

def speed(distance: float, time: float): float = distance / time 

and can used this:

speed(distance = 100, time = 10) 

or

speed(time = 10, distance = 100) 

default arguments:

scala lets specify default values function parameters. example:

def printtime(out: java.io.printstream = console.out) =     out.println("time = "+ system.currenttimemillis()) 

then can call printtime without giving output stream this:

printtime() 

repeated arguments:

scala allows indicate last parameter function may repeat. example:

def echo(args: string*) =    (arg <- args)      println(arg) 

then can use this:

echo() echo("one") echo("hello", "world!")