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| author | Austin Seipp <austin@well-typed.com> | 2013-09-15 16:06:30 -0500 |
|---|---|---|
| committer | Austin Seipp <austin@well-typed.com> | 2013-09-15 16:06:33 -0500 |
| commit | 769bfc7332a89e8f022e3c1b9f5ba3a2a13f88c6 (patch) | |
| tree | 01339f1e876288a9ffd24659296bc9d80b708593 /docs | |
| parent | bb532682aa47c30dfd49039c5ab282352d38dac0 (diff) | |
| download | haskell-769bfc7332a89e8f022e3c1b9f5ba3a2a13f88c6.tar.gz | |
Mention new solver for -XTypeNats in release notes.
Signed-off-by: Austin Seipp <austin@well-typed.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/users_guide/7.8.1-notes.xml | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/docs/users_guide/7.8.1-notes.xml b/docs/users_guide/7.8.1-notes.xml index 3d045bc5d2..40b48d11e6 100644 --- a/docs/users_guide/7.8.1-notes.xml +++ b/docs/users_guide/7.8.1-notes.xml @@ -30,6 +30,26 @@ <listitem> <para> + GHC can now perform simple evaluation of type-level + natural numbers, when using the + <literal>TypeNats</literal> extension. For example, + given a type-level constraint such as <literal>(x + 3) + ~ 5</literal>, GHC is able to infer that + <literal>x</literal> is 2. Similarly, GHC can now + understand type-level identities such as <literal>x + + 0 ~ x</literal>. + </para> + + <para> + Note that the solving of these equations is only used + to resolve unification variables - it does not + generate new facts in the type checker. This is + similar to how functional dependencies work. + </para> + </listitem> + + <listitem> + <para> It is now possible to declare a 'closed' <literal>type family</literal> when using the <literal>TypeFamilies</literal> extension. A closed |