anonymous function
function literal
function value
lambda expression
closure


5                // anonymous number, number literal 

val x = 5;       // give the number a name

0xabc            // anonymous number, number literal (in hex)

val y = 0xabc;  // give the number a name


fn x => x*x + 4   // anonymous function, functionn literal

val g = fn x => x^*x + 4;  // give the anonymous function a name, give the function literal a name

fun g x = x*x + 4;  // ML function definition


fn x y => x*y + 4                // ML
fun x y -> x*y + 4               // Ocaml, F#
\x y -> x*y + 4                  // Haskell
lambda x, y: x*y + 4             // Python
function(x, y){return x*y + 4;}  // JavaScript
(x, y) => x*y + 4                // JavaScript
[](int x, y)->{return x*y + 4;}  // C++
(x, y) -> x*y + 4                // Java
(lambda (x y) (+ (* x y) 4))     // Lisp, Scheme