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view src/option_key_fn.sml @ 2307:6ae9a2784a45

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author Adam Chlipala <adam@chlipala.net>
date Sun, 20 Dec 2015 14:39:50 -0500
parents e4a7e3cd6f11
children
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functor OptionKeyFn(K : ORD_KEY)
        : ORD_KEY where type ord_key = K.ord_key option = struct

type ord_key = K.ord_key option

val compare =
 fn (NONE, NONE) => EQUAL
  | (NONE, _) => LESS
  | (_, NONE) => GREATER
  | (SOME x, SOME y) => K.compare (x, y)

end