diff options
Diffstat (limited to 'docs/users_guide/9.2.1-notes.rst')
| -rw-r--r-- | docs/users_guide/9.2.1-notes.rst | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/docs/users_guide/9.2.1-notes.rst b/docs/users_guide/9.2.1-notes.rst index 5e0bf1c317..521427b4d9 100644 --- a/docs/users_guide/9.2.1-notes.rst +++ b/docs/users_guide/9.2.1-notes.rst @@ -65,6 +65,21 @@ Language record pattern synonyms. In particular, it is possible for a single module to define multiple pattern synonyms using the same field names. +* Because of simplifications to the way that GHC typechecks operator sections, + operators with nested ``forall``\ s or contexts in their type signatures might + not typecheck when used in a section. For instance, the ``g`` function below, + which was accepted in previous GHC releases, will no longer typecheck: :: + + f :: a -> forall b. b -> a + f x _ = x + + g :: a -> a + g = (`f` "hello") + + ``g`` can be made to typecheck once more by eta expanding it to + ``\x -> x \`f\` "hello"``. For more information, see + :ref:`simple-subsumption`. + Compiler ~~~~~~~~ |