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[smlnj] Annotation of /sml/trunk/src/system/Basis/Implementation/option.sml
Annotation of /sml/trunk/src/system/Basis/Implementation/option.sml
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monnier |
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(* option.sml
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*
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* COPYRIGHT (c) 1997 AT&T Labs Research.
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*)
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structure Option : OPTION =
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struct
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open Assembly (* for type 'a option *)
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exception Option
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fun getOpt (SOME x, y) = x
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| getOpt (NONE, y) = y
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fun isSome (SOME _) = true
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| isSome NONE = false
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fun valOf (SOME x) = x
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| valOf _ = raise Option
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fun filter pred x = if (pred x) then SOME x else NONE
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fun join (SOME opt) = opt
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| join NONE = NONE
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fun map f (SOME x) = SOME(f x)
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| map f NONE = NONE
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fun mapPartial f (SOME x) = f x
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| mapPartial f NONE = NONE
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fun compose (f, g) x = map f (g x)
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fun composePartial (f, g) x = mapPartial f (g x)
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end;
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