[Haskell-cafe] how do I pass customization items in syb code?

[Alex Jacobson]

I'm looking at the XML SYB example 
http://www.cs.vu.nl/boilerplate/testsuite/xmlish/Main.hs

I'd like to find a way to pass other type customizations as arguments to 
data2content and content2data.

I modified data2Content as follows:

   data2content f =         element
                    `ext1Q` list
                    `extQ`  string 
                    `extQ`  f

But I can't figure out how to give f a type such that 
  
    (data2Content $ myFooElem `extQ` myBarElem) 

operates on both Foo and Bar elements. Right now I am giving f the type 
f::(a->[Content]) which compiles but causes the wrong behavior.

Any recommendations on how to fix this?

-Alex-