[GHC] #6022: GHC infers over-general types

[GHC]

#6022: GHC infers over-general types
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              Reporter:  simonpj     |            Owner:  simonpj
                  Type:  bug         |           Status:  closed
              Priority:  normal      |        Milestone:  7.10.1
             Component:  Compiler    |          Version:  7.4.1
            Resolution:  duplicate   |         Keywords:
      Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:  #8883
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Changes (by thomie):

 * status:  new => closed
 * resolution:   => duplicate
 * related:   => #8883


Comment:

 I now realize HEAD does exactly that, see #8883. I'm not sure if an extra
 regression is needed, but here's what it would look like:

 {{{
 $ cat T6022.hs
 module T6022 where
 f x = x + head

 $ ghc-7.9.20141125 T6022.hs
 [1 of 1] Compiling T6022            ( T6022.hs, T6022.o )

 T6022.hs:2:1:
     Non type-variable argument in the constraint: Num ([a] -> a)
     (Use FlexibleContexts to permit this)
     When checking that ‘f’ has the inferred type
       f :: forall a. Num ([a] -> a) => ([a] -> a) -> [a] -> a
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/6022#comment:10>
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