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| -rw-r--r-- | docs/users_guide/8.10.1-notes.rst | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/docs/users_guide/8.10.1-notes.rst b/docs/users_guide/8.10.1-notes.rst index 8ed46e7f36..8bb5f62533 100644 --- a/docs/users_guide/8.10.1-notes.rst +++ b/docs/users_guide/8.10.1-notes.rst @@ -153,6 +153,20 @@ Language by the right-hand side of ``F2``\'s equation, this now needs ``-XUndecidableInstances``. The problem is very much akin to its need to detect some functional dependencies. +- The pattern-match coverage checker received a number of improvements wrt. + correctness and performance. + + Checking against user-defined COMPLETE pragmas + "just works" now, so that we could move away from the + `complicated procedure for disambiguation <https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#disambiguating-between-multiple-complete-pragmas>`__ + we had in place before. + + Previously, the checker performed really badly on some inputs and had no + good story for graceful degradation in these situations. These situations + should occur much less frequently now and degradation happens much more + smoothly, while still producing useful, sound results (see + :ghc-flag:`-fmax-pmcheck-models`). + Compiler ~~~~~~~~ |