Lambda expressions are just (anonymous) functions.
f(x) = x can be expressed as x→x
f(x, y) = x*x + y*y can be expressed as x, y→x*x + y*y
In simple Java terms,
1. Return an int 23 with a void argument
int j = { => 23 }.invoke();
2. Closure with 1 argument, convert 23 kilograms to pounds
double j = { double kilograms => kilograms*2.2D }.invoke(23);
3. Closure with 2 arguments, get the sum of the 2 squares
int squareSum = { int x, int y => (x*x) + (y*y) }.invoke(2,3);
4. Closure returning an instance and invoking an instance method
{ new RocketLauncher() }.invoke().fire();
Every time a closure is created at compile time, an interface is automatically created for each expression having an invoke method with a signature depending on the number of arguments, then an anonymous subclass of this interface is constructed.
Enjoy!
