[GHC] #10585: Implement proper bidirectional type inference

[GHC]

#10585: Implement proper bidirectional type inference
-------------------------------------+-------------------------------------
        Reporter:  goldfire          |                   Owner:  goldfire
            Type:  bug               |                  Status:  closed
        Priority:  normal            |               Milestone:
       Component:  Compiler (Type    |                 Version:  7.10.1
  checker)                           |                Keywords:
      Resolution:  wontfix           |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------
Changes (by goldfire):

 * status:  new => closed
 * resolution:   => wontfix


Comment:

 Bah. Well, I tried doing this, and it just made everything worse.

 The problem is that, in the nice simple systems in published papers, there
 are only a few forms that can make good use of an expected type
 (abstractions being the poster child here). However, in GHC, it's just
 much, much more complicated, where the vast majority of expression forms
 can make good use of an expected return type. So the structural changes I
 was hoping would reduce the possibility of errors only improve a few
 cases, while making the whole structure more intricate. Not worth it.

 I will add a Note though explaining why there aren't two typechecker
 functions, though.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10585#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler