partial support for lateral

Language/SQL/SimpleSQL/Parser.lhs

@@ -505,6 +505,7 @@ tref
 >     tref = nonJoinTref >>= optionSuffix joinTrefSuffix
 >     nonJoinTref = choice [try (TRQueryExpr <$> parens queryExpr)
 >                          ,TRParens <$> parens tref
+>                          ,TRLateral <$> (try (keyword_ "lateral") *> tref)
 >                          ,try (TRFunction <$> identifierString
 >                                           <*> parens (commaSep scalarExpr))
 >                          ,TRSimple <$> identifierString]
@@ -690,7 +691,7 @@ keyword parser also
 >     ["select", "as", "from", "where", "having", "group", "order"
 >     ,"limit", "offset"
 >     ,"inner", "left", "right", "full", "natural", "join"
->     ,"cross", "on", "using"
+>     ,"cross", "on", "using", "lateral"
 >     ,"when", "then", "case", "end", "in"
 >     ,"except", "intersect", "union"]
 

Language/SQL/SimpleSQL/Pretty.lhs

@@ -182,6 +182,7 @@
 >         ,nest 5 $ vcat $ punctuate comma $ map tr ts]
 >   where
 >     tr (TRSimple t) = text t
+>     tr (TRLateral t) = text "lateral" <+> tr t
 >     tr (TRFunction f as) =
 >         text f <> parens (commaSep $ map scalarExpr as)
 >     tr (TRAlias t a cs) =

Language/SQL/SimpleSQL/Syntax.lhs

@@ -197,6 +197,8 @@ I'm not sure if this is valid syntax or not.
 >               | TRQueryExpr QueryExpr
 >                 -- | from function(args)
 >               | TRFunction String [ScalarExpr]
+>                 -- | from lateral t
+>               | TRLateral TableRef
 >                 deriving (Eq,Show,Read)
 
 TODO: add function table ref