git.iko.soy/project-m36
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add some notes on key inclusion dependencies for Maybe types
d99208cAgentM
src/lib/ProjectM36/DataTypes/Maybe.hs+9
compare with master
unifiedsplit
@@ -27,3 +27,12 @@ maybeAtomFunctions = HS.fromList [
27 atomFuncBody = AtomFunctionBody Nothing $ \(defaultAtom:(ConstructedAtom dConsName _ (atomVal:_)):_) -> if atomTypeForAtom defaultAtom /= atomTypeForAtom atomVal then Left AtomFunctionTypeMismatchError else if dConsName == "Nothing" then pure defaultAtom else pure atomVal
27 atomFuncBody = AtomFunctionBody Nothing $ \(defaultAtom:(ConstructedAtom dConsName _ (atomVal:_)):_) -> if atomTypeForAtom defaultAtom /= atomTypeForAtom atomVal then Left AtomFunctionTypeMismatchError else if dConsName == "Nothing" then pure defaultAtom else pure atomVal
28 }
28 }
29 ]
29 ]
30+
31+{- To create an inclusion dependency for uniqueness for "Just a" values only
32+person := relation{name Text, boss Maybe Text}{tuple{name "Steve",boss Nothing}, tuple{name "Bob", boss Just "Steve"}}
33+:showexpr ((relation{tuple{}}:{a:=person where ^isJust(@boss)}):{b:=count(@a)}){b}
34+:showexpr ((relation{tuple{}}:{a:=person{boss} where ^isJust(@boss)}):{b:=count(@a)}){b}
35+constraint uniqueJust ((relation{tuple{}}:{a:=person where ^isJust(@boss)}):{b:=count(@a)}){b} in ((relation{tuple{}}:{a:=person{boss} where ^isJust(@boss)}):{b:=count(@a)}){b}
36+person := relation{name Text, boss Maybe Text}{tuple{name "Steve",boss Nothing}, tuple{name "Bob", boss Just "Steve"}, tuple{name "Jim", boss Just "Steve"}}
37+ERR: InclusionDependencyCheckError "uniqueJust"
38+-}