diff options
| -rw-r--r-- | docs/users_guide/ffi-chap.xml | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/docs/users_guide/ffi-chap.xml b/docs/users_guide/ffi-chap.xml index acd6f72f7c..0f9cfba483 100644 --- a/docs/users_guide/ffi-chap.xml +++ b/docs/users_guide/ffi-chap.xml @@ -73,7 +73,13 @@ OK: foreign import prim "foo" foo :: ByteArray# -> (# Int#, Int# #) </programlisting> This is used to import functions written in Cmm code that follow an - internal GHC calling convention. This feature is not intended for + internal GHC calling convention. The arguments and results must + be unboxed types, except that an argument may be of type + <literal>Any</literal> (by way of <literal>unsafeCoerce#</literal>) + and the result type is allowed to be an unboxed tuple + </para> + <para> + This feature is not intended for use outside of the core libraries that come with GHC. For more details see the <ulink linkend="http://ghc.haskell.org/trac/ghc/wiki/Commentary/PrimOps"> GHC developer wiki</ulink>. |