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POoverloading F# active patterns
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copied!<p>I am fairly new to F# and active patterns, and I ran across an anomoly that I can't explain.</p> <pre><code>module Eval = let (|Bet|Pass|) (test:BetChoice) = match test with | BetChoice.Bet -> Bet | BetChoice.Pass -> Pass let (|NoBet|Bet|Pass|) (test:Nullable<BetChoice>) : Choice<unit, unit, unit> = match test.HasValue with | true -> match test.Value with | BetChoice.Bet -> Bet | BetChoice.Pass -> Pass | false -> NoBet let FlipByWinner ((value:int), (awins:bool)) = match awins with | true -> (value, -value) | false -> (-value, value) let Evaluation (awins:bool) (player11:BetChoice) (player21:BetChoice) (player12:Nullable<BetChoice>) = match player11 with | Pass -> match player21 with | Pass -> FlipByWinner(1, awins) | Bet-> match player12 with | Bet -> FlipByWinner(2, awins) | Pass -> FlipByWinner(1, false) | NoBet -> raise (System.ArgumentException("invalid strategy")) | Bet -> match player21 with | Bet -> FlipByWinner (2, awins) | Pass -> FlipByWinner (1, false) </code></pre> <p>This doesn't compile. With a minor tweak I can make it work as intended, but the fact that I don't know exactly what is going on makes me a little nervous... the second pattern can get renamed to "(|NoBet|Bet1|Pass1|)" and it's associated patterns changed throughout the code, then it works, but I don't really get why this has a type mismatch exception.</p> <p>Also is there a good way of dealing with 2 active patterns that are almost identical, but not quite? seems like there should be a way to factor the common stuff together. (as a side note, it looks like the indenting got messed up in the copy/paste, this is all part of the module Eval properly).</p>

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