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author | Sebastian Graf <sebastian.graf@kit.edu> | 2020-01-27 14:18:04 +0100 |
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committer | Ben Gamari <ben@smart-cactus.org> | 2020-02-06 17:23:17 -0500 |
commit | 4f3db327a1b30bd77368948ba87a84ba9ce34dca (patch) | |
tree | 8d3699dc1b5ddb1496d06c389397e61b366e1c63 | |
parent | ac08f13fbc8adff4ff792228994f8feb3b59b6f3 (diff) | |
download | haskell-4f3db327a1b30bd77368948ba87a84ba9ce34dca.tar.gz |
8.10 Release notes for improvements to the pattern-match checker
A little late to the game, but better late than never.
(cherry picked from commit 873e7847bab694d2a00bfafa1e66b6642ea3c04c)
-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 836508d030..c580443093 100644 --- a/docs/users_guide/8.10.1-notes.rst +++ b/docs/users_guide/8.10.1-notes.rst @@ -159,6 +159,20 @@ Language by the right-hand side of ``F2``\'s equation, this now needs :ghc-flag:`-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 ~~~~~~~~ |