From: simonpj@microsoft.com <unknown>
Date: Wed, 2 May 2007 10:38:15 +0000 (+0000)
Subject: Document the fact that you can't make a newtype of an unboxed data type
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=613737b1e6b7f6660536b8c8d959639cb386f5cf;p=ghc-hetmet.git

Document the fact that you can't make a newtype of an unboxed data type
---

diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml
index 4ed8c2a..61cff6e 100644
--- a/docs/users_guide/glasgow_exts.xml
+++ b/docs/users_guide/glasgow_exts.xml
@@ -381,6 +381,13 @@ worse, the unboxed value might be larger than a pointer
 (<literal>Double&num;</literal> for instance).
 </para>
 </listitem>
+<listitem><para> You cannot define a newtype whose representation type
+(the argument type of the data constructor) is an unboxed type.  Thus,
+this is illegal:
+<programlisting>
+  newtype A = MkA Int#
+</programlisting>
+</para></listitem>
 <listitem><para> You cannot bind a variable with an unboxed type
 in a <emphasis>top-level</emphasis> binding.
 </para></listitem>