[Haskell-cafe] GHC 7.4 and TypeSynonymInstances

Antoine Latter aslatter at gmail.com
Thu Jun 7 03:05:28 CEST 2012

On Fri, Apr 20, 2012 at 12:25 AM, Ivan Lazar Miljenovic
<ivan.miljenovic at gmail.com> wrote:
> Has there been a change in the behaviour/requirement of
> TypeSynonymInstances as of GHC-7.4.1? (Not sure if this behaviour
> occurs with 7.2.1 as I don't have it installed)
> I had an instance for String for a class which ghc accepted whilst
> using FlexibleInstances; however, when trying to load it in 7.0.* it
> stated that TypeSynonymInstances was needed (which I forgot to add
> since it didn't seem to need it).

Previously FlexibleInstances implied TypeSynonymInstances, I think?

I can't find any documentation for the change or a bug report, so I
could be mis-remembering.


More information about the Haskell-Cafe mailing list