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| -rw-r--r-- | docs/users_guide/8.2.1-notes.rst | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/docs/users_guide/8.2.1-notes.rst b/docs/users_guide/8.2.1-notes.rst index b3dd2de93e..9a7236b42b 100644 --- a/docs/users_guide/8.2.1-notes.rst +++ b/docs/users_guide/8.2.1-notes.rst @@ -167,6 +167,16 @@ Compiler "StillWorks" forall x. f (Just x) = e +- Type synonyms can no longer appear in the class position of an instance. + This means something like this is no longer allowed: :: + + type ReadShow a = (Read a, Show a) + instance Read Foo + instance Show Foo + instance ReadShow Foo -- illegal + + See :ghc-ticket:`13267`. + GHCi ~~~~ |