@@ -43,6 +43,8 @@ import Data.Time.LocalTime ( TimeOfDay, LocalTime )
4343import Data.UUID ( UUID )
4444
4545
46+-- | The class of database types that support the @<@, @<=@, @>@ and @>=@
47+-- operators.
4648type DBOrd :: Type -> Constraint
4749class DBEq a => DBOrd a
4850instance DBOrd Bool
@@ -71,6 +73,7 @@ instance Sql DBOrd a => DBOrd (NonEmpty a)
7173instance {-# OVERLAPPING #-} DBOrd Opaque
7274
7375
76+-- | The class of database types that support the @max@ aggregation function.
7477type DBMax :: Type -> Constraint
7578class DBOrd a => DBMax a
7679instance DBMax Bool
@@ -97,6 +100,7 @@ instance Sql DBMax a => DBMax [a]
97100instance Sql DBMax a => DBMax (NonEmpty a)
98101
99102
103+-- | The class of database types that support the @min@ aggregation function.
100104type DBMin :: Type -> Constraint
101105class DBOrd a => DBMin a
102106instance DBMin Bool