add window functions (without frames

Language/SQL/SimpleSQL/Parser.lhs

@@ -161,6 +161,19 @@ to be.
 >               return $ App i es
 >           _ -> return $ AggregateApp i d es (fromMaybe [] od)
 
+> windowSuffix :: ScalarExpr -> P ScalarExpr
+> windowSuffix e@(App f es) =
+>     choice [try (keyword_ "over")
+>             *> parens (WindowApp f es
+>                        <$> option [] partitionBy
+>                        <*> option [] orderBy)
+>            ,return e]
+>   where
+>     partitionBy = try (keyword_ "partition") >>
+>         keyword_ "by" >>
+>         commaSep1 scalarExpr'
+
+> windowSuffix e = return e
 
 > scase :: P ScalarExpr
 > scase =
@@ -308,7 +321,7 @@ postgresql handles this
 >                     ,extract
 >                     ,subquery
 >                     ,prefixUnaryOp
->                     ,try app
+>                     ,(try app) >>= windowSuffix
 >                     ,try dottedIden
 >                     ,identifier
 >                     ,sparens]

Language/SQL/SimpleSQL/Pretty.lhs

@@ -39,6 +39,15 @@ back into SQL source text. It attempts to format the output nicely.
 >                <+> commaSep (map scalarExpr es)
 >                <+> orderBy od)
 
+> scalarExpr (WindowApp f es pb od) =
+>     text f <> parens (commaSep $ map scalarExpr es)
+>     <+> text "over"
+>     <+> parens ((case pb of
+>                     [] -> empty
+>                     _ -> text "partition by"
+>                           <+> nest 4 (commaSep $ map scalarExpr pb))
+>                 <+> orderBy od)
+
 > scalarExpr (SpecialOp nm [a,b,c]) | nm `elem` ["between", "not between"] =
 >   sep [scalarExpr a
 >       ,text nm <+> scalarExpr b

Language/SQL/SimpleSQL/Syntax.lhs

@@ -24,6 +24,7 @@
 >                 | AggregateApp String (Maybe Duplicates)
 >                                [ScalarExpr]
 >                                [(ScalarExpr,Direction)]
+>                 | WindowApp String [ScalarExpr] [ScalarExpr] [(ScalarExpr,Direction)]
 >                   -- the binop, prefixop and postfix op
 >                   -- are used for symbol and keyword operators
 >                   -- these are used even for the multiple keyword