#10281: Type error with Rank-n-types -------------------------------------+------------------------------------- Reporter: rhjl | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.10.1 checker) | Keywords: Resolution: | Architecture: Operating System: Unknown/Multiple | Unknown/Multiple Type of failure: GHC rejects | Test Case: valid program | Peirce_eq_LEM.hs Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by simonpj): Replying to [comment:6 rhjl]:
I find your explanation of impredicative polymorphism better than the one given in the GHC manual: ... I think that a remark of this sort in the section on rank-n-types of the GHC manual would also help.
Could you propose some actual, concrete sentences to add or change in user manual? Then I'll just make the change. As a bona fide user you are in a far better position to draft the words than me.
By the way: this issue with impredicative instantiations precludes the use of `($)` and `(.)` to get rid of excessive parenthesis in certain situations. Is there a workaround?
Becuase of this `($)` has its own special typing rule in GHC. But `(.)` does not (yet). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10281#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler