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Fix loop in IsSubList

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See #293.
This commit is contained in:
Julian K. Arni 2015-12-16 13:41:18 +01:00
parent 82deaeb63c
commit b20edfd96a
1 changed files with 5 additions and 4 deletions
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9
servant/src/Servant/Utils/Links.hs
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@ -180,12 +180,13 @@ type family IsElem endpoint api :: Constraint where
IsElem e e = ()
IsElem e a = IsElem' e a
type family IsSubList a b :: Constraint where
IsSubList '[] b = ()
IsSubList '[x] (x ': xs) = ()
IsSubList '[x] (y ': ys) = IsSubList '[x] ys
IsSubList (x ': xs) y = IsSubList '[x] y `And` IsSubList xs y
IsSubList (x ': xs) y = Elem x y `And` IsSubList xs y
type family Elem e es :: Constraint where
Elem x (x ': xs) = ()
Elem y (x ': xs) = Elem y xs
-- Phantom types for Param
data Query