diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/users_guide/glasgow_exts.rst | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/docs/users_guide/glasgow_exts.rst b/docs/users_guide/glasgow_exts.rst index 0ef0d053af..b1e9bc6722 100644 --- a/docs/users_guide/glasgow_exts.rst +++ b/docs/users_guide/glasgow_exts.rst @@ -10686,7 +10686,7 @@ Visible type application ======================== .. extension:: TypeApplications - :shortdesc: Enable type application syntax. + :shortdesc: Enable type application syntax in terms and types. :since: 8.0.1 @@ -10707,6 +10707,10 @@ is an identifier (the common case), its type is considered known only when the identifier has been given a type signature. If the identifier does not have a type signature, visible type application cannot be used. +GHC also permits visible kind application, where users can declare the kind +arguments to be instantiated in kind-polymorphic cases. Its usage parallels +visible type application in the term level, as specified above. + .. _inferred-vs-specified: Inferred vs. specified type variables @@ -10864,8 +10868,8 @@ the rules in the subtler cases: application. If you want to specify only the second type argument to ``wurble``, then you can say ``wurble @_ @Int``. The first argument is a wildcard, just like in a partial type signature. - However, if used in a visible type application, it is *not* - necessary to specify :extension:`PartialTypeSignatures` and your + However, if used in a visible type application/visible kind application, + it is *not* necessary to specify :extension:`PartialTypeSignatures` and your code will not generate a warning informing you of the omitted type. The section in this manual on kind polymorphism describes how variables @@ -12251,10 +12255,10 @@ Anonymous and named wildcards *can* occur on the left hand side of a type or data instance declaration; see :ref:`type-wildcards-lhs`. -Anonymous wildcards are also allowed in visible type applications -(:ref:`visible-type-application`). If you want to specify only the second type -argument to ``wurble``, then you can say ``wurble @_ @Int`` where the first -argument is a wildcard. +Anonymous wildcards are also allowed in visible type applications/ visible kind +applications (:ref:`visible-type-application`). If you want to specify only the +second type argument to ``wurble``, then you can say ``wurble @_ @Int`` where +the first argument is a wildcard. Standalone ``deriving`` declarations permit the use of a single, extra-constraints wildcard, like so: :: |