#11343: Unable to infer type when using DuplicateRecordFields -------------------------------------+------------------------------------- Reporter: mpickering | Owner: adamgundry Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.11 checker) | 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: | -------------------------------------+------------------------------------- Changes (by adamgundry): * owner: => adamgundry * failure: None/Unknown => GHC rejects valid program * component: Compiler => Compiler (Type checker) * version: 7.10.3 => 7.11 * type: bug => feature request Comment: By design, we don't do any inference to determine which record type is meant in this kind of situation. Instead, the type must be pushed in to the update, or the record expression being updated must have a type signature. Thus either of these should work: {{{#!hs print (aThing { a = 5 } :: A) print ((bThing :: B) { a = 5 } ) }}} I suppose we could add a special case for when the record expression is a variable whose type is known, which would cover this example. I'm not sure if it's a good idea to accumulate too many special cases, but perhaps this case is common enough that it's worthwhile? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11343#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler