[Haskell-cafe] GHC 7.4 and TypeSynonymInstances

Ivan Lazar Miljenovic ivan.miljenovic at gmail.com
Fri Apr 20 07:25:36 CEST 2012

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).

All I could find in the release notes was that as of 7.2.1, both
extensions were needed, not that one implied the other:

Is this behaviour deliberate, or a bug?

Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com

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