[GHC] #14901: dsrun014 fails with most ways

[GHC]

#14901: dsrun014 fails with most ways
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        Reporter:  alpmestan         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.5
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:  dsrun014
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 alpmestan, this is a consequence of the fact that `seq` has special typing
 rules. See `Note [Typing rule for seq]` in
 http://git.haskell.org/ghc.git/blob/efc844f5b955385d69d8e20b80d38311083a6665:/compiler/typecheck/TcExpr.hs#l334
 how this is implemented (and why it's special).

 `pseq` does not have corresponding special typing rules, which is why it
 fails when given an unlifted argument. Should `pseq` be given similar
 magic? I'm not sure.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14901#comment:4>
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