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| author | Vladislav Zavialov <vlad.z.4096@gmail.com> | 2018-10-04 09:17:55 -0400 |
|---|---|---|
| committer | Ryan Scott <ryan.gl.scott@gmail.com> | 2018-10-04 09:17:55 -0400 |
| commit | bd7898537768f936d05c0c83eef1cd9b00933347 (patch) | |
| tree | db16292d6c32f6ef04ff829178cacc6709d00a6d /docs/users_guide/8.8.1-notes.rst | |
| parent | fc2ff6dd7496a33bf68165b28f37f40b7d647418 (diff) | |
| download | haskell-bd7898537768f936d05c0c83eef1cd9b00933347.tar.gz | |
Parse the (!) type operator and allow type operators in existential context
Summary:
Improve the way `(!)`, `(~)`, and other type operators are handled in the parser,
fixing two issues at once:
1. `(!)` can now be used as a type operator
that respects fixity and precedence (#15457)
2. Existential context of a data constructor
no longer needs parentheses (#15675)
In addition to that, with this patch it is now trivial to adjust precedence of
the `{-# UNPACK #-}` pragma, as suggested in
https://ghc.haskell.org/trac/ghc/ticket/14761#comment:7
There was a small change to API Annotations. Before this patch, `(~)` was a
strange special case that produced an annotation unlike any other type
operator. After this patch, when `(~)` or `(!)` are used to specify strictness they
produce AnnTilde and AnnBang annotations respectively, and when they are used
as type operators, they produce no annotations.
Test Plan: Validate
Reviewers: simonpj, bgamari, alanz, RyanGlScott
Reviewed By: RyanGlScott
Subscribers: RyanGlScott, rwbarton, mpickering, carter
GHC Trac Issues: #15457, #15675
Differential Revision: https://phabricator.haskell.org/D5180
Diffstat (limited to 'docs/users_guide/8.8.1-notes.rst')
| -rw-r--r-- | docs/users_guide/8.8.1-notes.rst | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/docs/users_guide/8.8.1-notes.rst b/docs/users_guide/8.8.1-notes.rst index e3a8d3ea22..00e532c6d1 100644 --- a/docs/users_guide/8.8.1-notes.rst +++ b/docs/users_guide/8.8.1-notes.rst @@ -40,6 +40,16 @@ Language terminating value of type ``Void``. Accordingly, GHC will not warn about ``K2`` (whereas previous versions of GHC would). +- ``(!)`` is now a valid type operator: :: + + type family a ! b + +- An existential context no longer requires parenthesization: :: + + class a + b + data D1 = forall a b. (a + b) => D1 a b + data D2 = forall a b. a + b => D2 a b -- now allowed + Compiler ~~~~~~~~ |