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I couldn't think of a better example at the time. Something that simultaneously matched several fields (whether destructured from one variable or not) and/or had guards would be a better example. Maybe something like this (in pseudo-ML): (* Look up order code for a Sci-Fi GadgetTM, units are in cm *)
let gadget_order_code width depth height color has_laser =
match (width depth height color has_laser) =
(* The original, simple code *)
| 5, 2, 1, Red, true -> "ZAP-X"
(* Most common width, color *)
| 4, d, h, Blue, true -> sprintf "ZAP-4-%d%d+" (str d) (str h) "+"
(* C for Custom Color *)
| 4, d, h, c, false -> "ZAP-4C-%d%d-%c" (str d) (str h) (color_code c)
(* Orange lasers are discontinued *)
| w, d, h, c, true when (w + d + h) < 15 and c != Orange ->
"ZAP-S-%d%d%d-%c" (str w) (str d) (str h) (color_code c)
| _, _, _, _, _ -> failwith "Unavailable"
That's a little complicated to determine with pattern matching or via a database, but doing it in a series of nested if statements would get mind boggling. |