[Git][ghc/ghc][master] Fix #16603 by documenting some important changes in changelogs
Marge Bot
gitlab at gitlab.haskell.org
Wed May 8 06:01:51 UTC 2019
Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC
Commits:
786e665b by Ryan Scott at 2019-05-08T05:55:45Z
Fix #16603 by documenting some important changes in changelogs
This addresses some glaring omissions from
`libraries/base/changelog.md` and
`docs/users_guide/8.8.1-notes.rst`, fixing #16603 in the process.
- - - - -
2 changed files:
- docs/users_guide/8.8.1-notes.rst
- libraries/base/changelog.md
Changes:
=====================================
docs/users_guide/8.8.1-notes.rst
=====================================
@@ -23,6 +23,21 @@ Full details
Language
~~~~~~~~
+- GHC now supports visible kind applications, as described in
+ `GHC proposal #15 <https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0015-type-level-type-applications.rst>`__. This extends the existing
+ :ref:`visible type applications <visible-type-application>` feature to permit
+ type applications at the type level (e.g., ``f :: Proxy ('Just @Bool 'True)``) in
+ addition to the term level (e.g., ``g = Just @Bool True``).
+
+- GHC now allows explicitly binding type variables in type family instances and
+ rewrite rules, as described in
+ `GHC proposal #7 <https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0007-instance-foralls.rst>`__. For instance: ::
+
+ type family G a b where
+ forall x y. G [x] (Proxy y) = Double
+ forall z. G z z = Bool
+ {-# RULES "example" forall a. forall (x :: a). id x = x #-}
+
- :extension:`ScopedTypeVariables`: The type variable that a type signature on
a pattern can bring into scope can now stand for arbitrary types. Previously,
they could only stand in for other type variables, but this restriction was deemed
@@ -76,6 +91,13 @@ Language
Compiler
~~~~~~~~
+- The final phase of the ``MonadFail`` proposal has been implemented.
+ Accordingly, the ``MonadFailDesugaring`` language extension is now
+ deprecated, as its effects are always enabled. Similarly, the
+ ``-Wnoncanonical-monadfail-instances`` flag is also deprecated, as there is
+ no longer any way to define a "non-canonical" ``Monad`` or ``MonadFail``
+ instance.
+
- New :ghc-flag:`-keep-hscpp-files` to keep the output of the CPP pre-processor.
- The :ghc-flag:`-Wcompat` warning group now includes :ghc-flag:`-Wstar-is-type`.
@@ -143,6 +165,13 @@ Template Haskell
longer included when reifying ``C``. It's possible that this may break some
code which assumes the existence of ``forall a. C a =>``.
+- Template Haskell has been updated to support visible kind applications and
+ explicit ``foralls`` in type family instances and ``RULES``. These required
+ a couple of backwards-incompatible changes to the ``template-haskell`` API.
+ Please refer to the
+ `GHC 8.8 Migration Guide <https://gitlab.haskell.org/ghc/ghc/wikis/migration/8.8#template-haskell-21500>`__
+ for more details.
+
- Template Haskell now supports implicit parameters and recursive do.
``ghc-prim`` library
@@ -164,6 +193,20 @@ Template Haskell
``base`` library
~~~~~~~~~~~~~~~~
+- The final phase of the ``MonadFail`` proposal has been implemented. As a
+ result of this change:
+
+ - The ``fail`` method of ``Monad`` has been removed in favor of the method of
+ the same name in the ``MonadFail`` class.
+
+ - ``MonadFail(fail)`` is now re-exported from the ``Prelude`` and
+ ``Control.Monad`` modules.
+
+ These are breaking changes that may require you to update your code. Please
+ refer to the
+ `GHC 8.8 Migration Guide <https://gitlab.haskell.org/ghc/ghc/wikis/migration/8.8#base-41300>`__
+ for more details.
+
- Support the characters from recent versions of Unicode (up to v. 12) in literals
(see :ghc-ticket:`5518`).
=====================================
libraries/base/changelog.md
=====================================
@@ -8,6 +8,14 @@
## 4.13.0.0 *TBA*
* Bundled with GHC *TBA*
+ * The final phase of the `MonadFail` proposal has been implemented:
+
+ * The `fail` method of `Monad` has been removed in favor of the method of
+ the same name in the `MonadFail` class.
+
+ * `MonadFail(fail)` is now re-exported from the `Prelude` and
+ `Control.Monad` modules.
+
* Fix `Show` instance of `Data.Fixed`: Negative numbers are now parenthesized
according to their surrounding context. I.e. `Data.Fixed.show` produces
syntactically correct Haskell for expressions like `Just (-1 :: Fixed E2)`.
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/commit/786e665b8dac5430c02089b39f7cb7572a5254d8
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/commit/786e665b8dac5430c02089b39f7cb7572a5254d8
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