Function composition (ML)

	(* 'b -> 'c) * ('a -> b') -> ('a -> 'c) *)
	fun compose(f,g) = fn x => f(g x)
	(* in ML you can compose functions like f o g *)
	fun sqrt_of_abs1 i = Math.sqrt (Real.fromInt (abs i))
	val sqrt_of_abs2 = Math.sqrt o Real.fromInt o abs
	(* we can also define our own infix operator to compose functions
	the other way around *)
	infix !>
	fun x !> f = f x
	fun sqrt_of_abs3 i = i !> abs !> Real.fromInt !> Math.sqrt
	fun backup1 (f,g) = fn x => case f x of
	NONE => g x
	| SOME => y

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