No subject

    snd $ fn' (zip [x] [a]) = fn [a]

I can see ways of doing this by altering fn, or by repeating some of fn in
the definition of fn', or (because in this case I know that if fn xs = x,
fn is returning the first x in xs and not any others), by doing something
nasty like:

  fn' xs = xs !! fromMaybe 0 (findIndex (\(_,a) -> a == fn (snd $ unzip
xs)) xs )

But it seems to me like there should be prettier solutions to this (that *do
not* involve changing the definition of fn). After all, this doesn't seem
like a rare pattern.

Anyone know if in fact there's a better way to go about it?

--f46d042de425749bab04dcc4c06b
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