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Diffstat (limited to 'docs/users_guide/9.4.1-notes.rst')
| -rw-r--r-- | docs/users_guide/9.4.1-notes.rst | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/docs/users_guide/9.4.1-notes.rst b/docs/users_guide/9.4.1-notes.rst index 345badec57..42791d7153 100644 --- a/docs/users_guide/9.4.1-notes.rst +++ b/docs/users_guide/9.4.1-notes.rst @@ -72,6 +72,17 @@ Compiler - New :ghc-flag:`-fprof-late` that adds automatic CCS annotations to all top level functions *after* core optimisation have been run. +- Typechecking plugins now support type-family rewriting. The ``TcPlugin`` + datatype now contains an extra field, ``tcPluginRewrite``, which allows + typechecking plugin authors to specify which type families should be + rewritten by the plugin, returning for each type family application a + ``TcPluginRewriteResult``. + In addition, typechecking plugins now have the ability to emit new constraints + at the same time as contradictions. To account for these changes, the + ``TcPluginResult`` datatype has been renamed to ``TcPluginSolveResult``, + which bundles pattern synonyms ``TcPluginOk`` and ``TcPluginContradiction`` + to recover the old interface. + - A new type of plugin: defaulting plugins. These plugins can propose defaults for ambiguous variables that would otherwise cause errors just like the built-in defaulting mechanism. |