#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 simonpj): In principle yes, but in the `wip/T2893` branch: * I deliberately never ''infer' a type with quantified constraints. It seems too easy to infer an elaborate, incomprehensible, and perhaps even insoluble, constraint when all that happened was a simple error on the programmer's part. * The design deliberately has `cls tys` or `tyvar tys` after the `=>` of a quantified constraint; not `a ~ Bool`. There are too many other ways to solve equalities! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14993#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler