#13262: Allow type synonym family application in instance head if it has no free variables -------------------------------------+------------------------------------- Reporter: ezyang | Owner: (none) Type: feature request | Status: new Priority: low | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: backpack Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: 12680 Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Let's not do this unless there is a really compelling reason. More complication. And soon you'll want {{{ type instance F (G [a]) = blah }}} to work, assuming that `G [a]` can reduce to (say) `[Tree a]`. This way lies madness. Let's not complicate the language of type patterns. Yet anyway. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13262#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler