Computing bound of a List with F#

Following code snippet shows how to compute bound (i.e the min and max elements) of a List using F#.

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 let rec bound (lst:int list) : (int*int) option = match lst with | [] -> None // Empty List | xhd::xtl -> match bound xtl with | None -> Some (xhd,xhd) // List with only 1 element | Some (x,y) -> Some ((if x>xhd then xhd else x), (if y
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Solution outlined here is quite trivial and use the pattern matching facilities of F#.  In case of an empty list (line 3), it returns `None`; otherwise, it returns the bound as `Some (int*int)`  (line 8).

Therefore, the signature of `bound` is given by-

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 val bound : lst:int list -> (int * int) option
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Output of `bound`

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 > bound [1;2;3;4];; val it : (int * int) option = Some (1, 4) > bound [1];; val it : (int * int) option = Some (1, 1) > bound [];; val it : (int * int) option = None
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