My OCaml solution to the Cleaner Code challenge (https://www.codeproject.com/articles/1083348/csharp-bad-practices-learn-how-to-make-a-good-code)

CleanerCode.ml

let accountFactor = function
  | `Simple -> 0.9
  | `Valuable -> 0.7
  | `MostValuable -> 0.5

let loyaltyFactor years =
  1.0 -. float(min years 5) /. 100.0

let applyDiscount price = function
  | `Unregistered -> price
  | `Registered(kind, years) ->
      price *. accountFactor kind *. loyaltyFactor years