#15800: Overlapping instances error with single instance -------------------------------------+------------------------------------- Reporter: roland | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): I've tried to improve the docs. The key is that GHC looks at ''both'' top level instances ''and'' in-scope constraints, not just the former. In the error messages they are listed as "Matching instances" and "Matching givens" respectively. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15800#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler