#12976: GHCi displays the kinds of unboxed tuples incorrectly -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): I say that this behavior is correct. As you report, the kind of `(#,#)` is `forall (r1 :: RuntimeRep) (r2 :: RuntimeRep). TYPE r1 -> TYPE r2 -> TYPE 'UnboxedTupleRep`. So once you provide a type argument (`(#,#) Int#`), then GHC must supply both `RuntimeRep` arguments. The second one defaults to `PtrRepLifted`. At the term level, we can then regeneralize, but you can't do that in types because there is no type-level lambda. An alternative to the current design would be to have {{{ (#,#) :: forall (r1 :: RuntimeRep). TYPE r1 -> forall (r2 :: RuntimeRep). TYPE r2 -> TYPE 'UnboxedTupleRep` }}} This is an improvement from a technical standpoint, but I wager humans would be even more confused here. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12976#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler