#12540: RFC: Allow not quantifying every top-level quantifiee -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: 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 Iceland_jack): (Example that tripped me up) I wanted to define a `Proxy`-less version of [https://hackage.haskell.org/package/generics-sop-0.2.2.0/docs/Generics- SOP-Classes.html#v:hcpure hcpure]. By muscle memory I quantified over the type variables in the context but the rest.. {{{#!hs hcpure_ :: forall h c xs. (HPure h, AllN h c xs) => (forall (a :: k). c a => f a) -> h f xs hcpure_ = hcpure (Proxy @c) }}} I read my types in linear order: Do I quantify over `a`? (''no'', it's higher rank) Do I quantify over `k`? (''optional'', must appear before `h`, `c` and `f` though). Do I quantify over `c`? (''never mind'' already did) Do I quantify over `f`? (''yes'') Did I do `h`, `f`, `xs` already? This is more analysis than my brain can do quickly :) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12540#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler