pattern matching question

[David Clark]

Can Clean pattern matching always be `compiled' into nested case
expressions.

For example, the compilation of

    f(G,G) = e1
    f(H,y) = e2
    f(G,y) = e

could be

    f(x,y) = case x of
               G -> case y of
                      G -> e1
                    else
                      e3
                    end
              |H -> e2
             else
               error
             end

More generally, can you suggest any papers or other reference for
pattern-matching in Clean?

- David and Sebastian