1 files changed, 15 insertions, 2 deletions
diff --git a/lib/sqlalchemy/sql/functions.py b/lib/sqlalchemy/sql/functions.py
index 7fce3b95b..c7a0f142d 100644
--- a/lib/sqlalchemy/sql/functions.py
+++ b/lib/sqlalchemy/sql/functions.py
@@ -36,12 +36,25 @@ class AnsiFunction(GenericFunction):
     def __init__(self, **kwargs):
         GenericFunction.__init__(self, **kwargs)
 
-
-class coalesce(GenericFunction):
+class ReturnTypeFromArgs(GenericFunction):
+    """Define a function whose return type is the same as its arguments."""
+    
     def __init__(self, *args, **kwargs):
         kwargs.setdefault('type_', _type_from_args(args))
         GenericFunction.__init__(self, args=args, **kwargs)
 
+class coalesce(ReturnTypeFromArgs):
+    pass
+
+class max(ReturnTypeFromArgs):
+    pass
+
+class min(ReturnTypeFromArgs):
+    pass
+
+class sum(ReturnTypeFromArgs):
+    pass
+
 class now(GenericFunction):
     __return_type__ = sqltypes.DateTime