#14993: QuantifiedConstraints and principal types -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 Resolution: | Keywords: | QuantifiedConstraints, wipT2893 Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by AntC): Aha! I'd forgotten OutsideIn(X) entertains implication constraints. If you're looking for explanation/documentation, section **4.2.1** (starting "costs to the programmer", "costs to the type inference engine") explain the rationale, and it still stands. Simon's saying quantified constraints must be explicitly given by a signature, never inferred. That's in line with many exotic type system features; and makes perfect sense. Would be worth testing the examples from section **2.4** by giving an explicit signature same as what the paper says would be inferred. Does that get `-XQuantifiedConstraints` to accept them? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14993#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler