Update docs for change in parsing behaviour of infix operators like in GHC 9

(cherry picked from commit d4c43df13d428b1acee2149618f8503580303486)

1 files changed, 8 insertions, 2 deletions

diff --git a/docs/users_guide/9.0.1-notes.rst b/docs/users_guide/9.0.1-notes.rst
index 0e83843dd1..31488eb2ac 100644
--- a/docs/users_guide/9.0.1-notes.rst
+++ b/docs/users_guide/9.0.1-notes.rst
@@ -246,9 +246,15 @@ Language
   as ``f (-123)``, but ``x-123`` as ``(-) x 123``. Before this amendment,
   :extension:`NegativeLiterals` caused ``x-123`` to be parsed as ``x(-123)``.
 
-* GHC now requires whitespace between infix operators and their arguments in
-  some cases where it was not previously necessary as the result of the
+* GHC is now more sensitive to whitespace between infix operators and their arguments,
+  requiring it in some cases where it was not previously necessary as the result of the
   :ref:`whitespace-sensitive operator parsing proposal <https://github.com/ghc-proposals/ghc-proposals/pull/229>`.
+  It also affects the usage of ``!``,``~`` and ``@`` as BangPatterns, irrefutable patterns
+  and type applications respectively.
+  This  means that expressions that were parsed as visible type applications
+  in previous versions when the ``@`` was surrounded by whitespace will now
+  be parsed as an operator application.
+  For more details see the `migration guide on the wiki <https://gitlab.haskell.org/ghc/ghc/-/wikis/migration/9.0#whitespace-sensitive-and->`.
 
 Compiler
 ~~~~~~~~