fourmolu-0.4.0.0: data/examples/declaration/value/function/comprehension/transform-monad.hs

{-# LANGUAGE MonadComprehensions #-}
{-# LANGUAGE TransformListComp #-}

quux' xs ys = [
  (x,
    y) |
  x <- xs,
  y <- ys,
  then
  group
  by -- First comment
    (x
      + y)
  using -- Second comment
    groupWith -- Third comment
  ]