Re: Changes to the type checker with respect to UndecidableInstances

Hi Simon, Thanks. So there was a bug in the type checker. Do you have a link to the ticket or commits which fixed the issue? Mitsutoshi 2014-12-30 19:56 GMT+09:00 Simon Peyton Jones simo...@microsoft.com: UndecidableInstances is supposed to be needed if GHC can’t prove that the instance

RE: Changes to the type checker with respect to UndecidableInstances

UndecidableInstances is supposed to be needed if GHC can't prove that the instance declarations terminate. But here it can be sure they terminate. GHC 7.6.3 didn't realise this. I'll modify the user manual to be clearer on this point. Simon From: Glasgow-haskell-users

Changes to the type checker with respect to UndecidableInstances

Hi, I found a difference between GHC 7.6.3 and 7.8.3 with respect to UndecidableInstances. https://gist.github.com/maoe/57a4346eb36aee159916 https://gist.github.com/maoe/57a4346eb36aee159916 7.6.3 requires UndecidableInstances to compile this snippet whereas 7.8.3 doesn't. What has changed