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annotate 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
rev   line source
ziv@2244 1 functor OptionKeyFn(K : ORD_KEY)
ziv@2244 2 : ORD_KEY where type ord_key = K.ord_key option = struct
ziv@2240 3
ziv@2240 4 type ord_key = K.ord_key option
ziv@2240 5
ziv@2240 6 val compare =
ziv@2240 7 fn (NONE, NONE) => EQUAL
ziv@2240 8 | (NONE, _) => LESS
ziv@2240 9 | (_, NONE) => GREATER
ziv@2240 10 | (SOME x, SOME y) => K.compare (x, y)
ziv@2240 11
ziv@2240 12 end