A few examples of how lexical scope works (ML)

A function body is evaluated in the environment where the function was defined (created).

	val x = 1
	fun f y =
	let
	val x = y + 1
	in
	fn z => x + y + z (* will return 2y + 1 + z *)
	end
	val x = 3 (* irrelevant *)
	val g = f 4 (* return a function that ads 9 to its argument *)
	val y = 5 (* irrelevant *)
	val z = g 6 (* get 15 *)
	(* output of program
	- use "lexical1.sml";
	[opening lexical1.sml]
	val x = <hidden-value> : int
	val f = fn : int -> int -> int
	val x = 3 : int
	val g = fn : int -> int
	val y = 5 : int
	val z = 15 : int
	val it = () : unit
	*)

view raw gistfile1.sml hosted with ❤ by GitHub

	fun f g =
	let
	val x = 3 (* irrelevant *)
	in
	g 2
	end
	val x = 4
	fun h y = x + y (* add 4 to its argument *)
	val z = f h (* get 6 *)
	(* output of program
	- use "lexical2.sml";
	[opening lexical2.sml]
	val f = fn : (int -> 'a) -> 'a
	val x = 4 : int
	val h = fn : int -> int
	val z = 6 : int
	val it = () : unit
	*)

view raw gistfile1.sml hosted with ❤ by GitHub