hub.darcs.net :: ross -> transformers -> issue

concrete functor and monad transformers

#100Can `runExceptT` become a record field of `ExceptT`

Other transformers like MaybeT already do it like this and it has a couple of advantages, e.g. GHC generates HasField instances for it and since it is a different symbol type internally, it also gets highlighted differently with semantic highlighting.

  • I just had a look and that is true for multiple other transformers. I would be happy to make the change for all of them.

  • A disadvantage is that you get a messier Show instance.

  • I have read the mailing list entries from back when the accessors were removed.

    I think I would argue that these days that disadvantage is outweighed by the substantial advantages.

    1. the HasField instance (which could admittedly also written by hand
    2. the advantages wrt imports and exports (import .. (ExceptT (..)))
    3. the more consistent look and feel with the rest of the library.

    Additionally, the Show argument only applies to ExceptT, afaict. E.g. AccumT which also doesn't have the record accessor cannot be Shown anyway.

    • status set to closed

    OK, I've done this

  • darcsden 1.2 beta built Jun 23 201810:48:19
  • report problems to simon