rapid_check_3_shrinking.hs

shrinking :: (Show a) => Shrink a -> a -> (a -> Result) -> Result
shrinking shrink arg runSub =
  let children = shrink arg                 -- Get the children of the current branch
      result = findFailing children runSub  -- Look for the first failure
  in case result of
      Nothing -> Success
      Just (shrunk, failure) ->             -- In case a failure is found
        shrinking shrink shrunk runSub      -- Try to shrink further the child
        <>                                  -- OR (in case it fails)
        addToCounterExample shrunk failure  -- Add child to the counter example