Comments in list lead to odd formatting for preceding element

[expipiplus1]

foo =
  [ ("xx", "xx")
  , ("xx", "xxx")
  , ("xx", "xxx")
  , ( "xx"
    , "xx"
    )
    --
  , ("xx" , "xxxxx")
  , ("xxx", "xxxxx")
  , ("xx" , "xx")
  ]

Note that the formatting of the element before the comment is not consistent with the other elements.

A workaround is butting the comment after the comma:

foo =
  [ ("xx" , "xx")
  , ("xx" , "xxx")
  , ("xx" , "xxx")
  , ("xx" , "xx")
  , -- xxxxxx xxx
    ("xx" , "xxxxx")
  , ("xxx", "xxxxx")
  , ("xx" , "xx")
  ]

[dschrempf]

Actually, similar behavior has led to a semantic error with Haddock for me:

Original code

( DataTypeI       
, DataTypeII(DataConstructor)
  -- * Haddock heading
, name
)

is formatted to

( DataTypeI
, DataTypeII
  ( DataConstructor
    -- * Haddock heading
  )
, name
)

which throws a Haddock error of the form

parse error on input ‘-- * Haddock heading’
source  >    |      
source  > 23 |     -- * Haddock heading
source  >    |     ^^^^^^^^^^^^

[expipiplus1]

@dschrempf That's probably worthy of it's own issue

[dschrempf]

Done, see #281.

[lspitzner]

I do agree that it is a separate issue, but I cannot help but mention that I ran into (an equivalent of) this while implementing #281. Heh.

I still need to write some tests before I push, but both seem to resolved locally.