@@ -19,6 +19,8 @@ import Rel8.Type ( DBType )
19import Data.Scientific ( Scientific )
19import Data.Scientific ( Scientific )
22+-- | The class of database types that support the @+@, @*@, @-@ operators, and
23+-- the @abs@, @negate@, @sign@ functions.
22type DBNum :: Type -> Constraint
24type DBNum :: Type -> Constraint
23class DBType a => DBNum a
25class DBType a => DBNum a
24instance DBNum Int16
26instance DBNum Int16
@@ -36,7 +38,7 @@ instance DBIntegral Int32
36instance DBIntegral Int64
38instance DBIntegral Int64
39−type DBFractional :: Type -> Constraint
41+-- | The class of database types that support the @/@ operator.
40class DBNum a => DBFractional a
42class DBNum a => DBFractional a
41instance DBFractional Float
43instance DBFractional Float
42instance DBFractional Double
44instance DBFractional Double