[GHC] #9586: Implement Traversable/Foldable-Burning-Bridges Proposal

[GHC]

#9586: Implement Traversable/Foldable-Burning-Bridges Proposal
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              Reporter:  hvr         |            Owner:  hvr
                  Type:  task        |           Status:  new
              Priority:  normal      |        Milestone:  7.10.1
             Component:              |          Version:
  libraries/base                     |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Difficult (2-5
  Unknown/Multiple                   |  days)
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:  #9621
             Test Case:              |
              Blocking:              |
Differential Revisions:  Phab:D209   |
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Description changed by hvr:

Old description:

> More details to follow. I've created this ticket to be able to refer to
> from related preparatory commits.
>
> In a nutshell the goal (more or less) of this proposal  is to be able to
> compile code like the following w/o errors (due to conflicting
> definitions):
>
> {{{#!hs
> module XPrelude (module X) where
>
> import Data.Foldable     as X
> import Data.Traversable  as X
> import Data.List         as X
> import Control.Monad     as X
> import Prelude           as X
> }}}

New description:

 More details to follow. I've created this ticket to be able to refer to
 from related preparatory commits.

 In a nutshell the FTP (Foldable/Traversable-Proposal) sub-goal of the BBP
 (Burning-Bridges-Proposal) includes to be able to compile code like the
 following w/o errors (due to conflicting definitions):

 {{{#!hs
 module XPrelude (module X) where

 import Data.Foldable     as X
 import Data.Traversable  as X
 import Data.List         as X
 import Control.Monad     as X
 import Prelude           as X
 }}}

 Other goals include to generalise/weaken type-signatures where possible
 w/o breaking (much) compatibility with existing code. An in-depth design-
 document is in the works.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9586#comment:25>
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