1%include verbatim.fmt
2\begingroup
3\let\origtt=\ttfamily
4\def\ttfamily#1{\origtt \makebox[0pt]{\phantom{X}}}
5\begin{code}
6unionBy           ::  (a -> a -> Bool) -> [a] -> [a] -> [a]
7unionBy eq xs ys  =   xs ++ foldl (flip (deleteBy eq))
8                                  (nubBy eq ys)
9\end{code}
10\endgroup
11