> On Aug 11, 2018, at 11:27 AM, Vassil Ognyanov Keremidchiev <var...@gmail.com>
> wrote:
>
> What are the new features there toward Dependent Typed Haskell?
Ben's link to
https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/8.6.1-notes.html
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/8.6.1-notes.html>
includes several items, pasted here:
* A new StarIsType
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-StarIsType>
language extension has been added which controls whether * is parsed as
Data.Kind.Type or a regular type operator. StarIsType
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-StarIsType>
is enabled by default.
* CUSKs now require all kind variables to be explicitly quantified. This was
already the case with TypeInType
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-TypeInType>,
but now PolyKinds
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-PolyKinds>
also exhibits this behavior.
* Functionality of TypeInType
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-TypeInType>
has been subsumed by PolyKinds
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-PolyKinds>,
and it is now merely a shorthand for PolyKinds
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-PolyKinds>,
DataKinds
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-DataKinds>,
and NoStarIsType
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-StarIsType>.
The users are advised to avoid TypeInType
<https://downloads.haskell.org/~ghc/8.6.1-beta1/docs/html/users_guide/glasgow_exts.html#extension-TypeInType>
due to its misleading name: the Type :: Type axiom holds regardless of whether
it is enabled.
These are small steps, to be sure, but there's quite a bit going on behind the
scenes. For example see the "Coercion Quantification" and "Type-level visible
type applications" to take place at HIW
(https://icfp18.sigplan.org/track/hiw-2018-papers#event-overview
<https://icfp18.sigplan.org/track/hiw-2018-papers#event-overview>).
There are also a great many proposals in play at
https://github.com/ghc-proposals/ghc-proposals
<https://github.com/ghc-proposals/ghc-proposals>
More to come in the future, of course!
Richard
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