[evincarofautumn]

Simon Peyton-Jones is (was?) known for writing blocks in “aligned” instead of “hanging” style, with separators in prefix:

    someFunction =
      do { foo
         ; mx <- bar
         ; y <- case mx of { Just x -> do { baz
                                          ; pure (quux x)
                                          }
                           ; Nothing -> do { fnord
                                           ; blurch
                                           }
                           }
         ; xyzz y
         }

I find it nice enough to read, particularly because it leads to rapidly increasing indentation and consequently discourages deeply nested code, but it’s a bit of a pain to edit & diff. I would write the above like this:

    someFunction = do
      foo
      mx <- bar
      y <- case mx of
        Just x -> do
          baz
          pure (quux x)
        Nothing -> do
          fnord
          blurch
      xyzz y

This prefix delimiter style is actually fairly standard in Haskell not for “do” notation, but for records and lists, since Haskell doesn’t allow a final trailing comma in these structures:

    list :: [Text]
    list =
      [ "this"
      , "that"
      , "the other thing"
      ]

    data Numbers = Numbers
      { numI :: Int
      , numF :: Double
      , numS :: Text
      }

    record = Numbers
      { numI = 1
      , numF = 1.0
      , numS = "one"
      }