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| -rw-r--r-- | docs/users_guide/safe_haskell.xml | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/docs/users_guide/safe_haskell.xml b/docs/users_guide/safe_haskell.xml index 07da84fe16..abca32a71f 100644 --- a/docs/users_guide/safe_haskell.xml +++ b/docs/users_guide/safe_haskell.xml @@ -293,6 +293,12 @@ compilation error will occur. A simple way to think of this is a <emphasis>same origin policy</emphasis> for overlapping instances defined in Safe compiled modules.</listitem> + <listitem><emphasis>Data.Typeable</emphasis> — We restrict Typeable + instances to only derived ones (offered by GHC through the + <link linkend="deriving-typeable"><option>-XDeriveDataTypeable</option> + </link> extension). Hand crafted instances of the Typeable type class + are not allowed in Safe Haskell as this can easily be abused to + unsafely coerce between types.</listitem> </itemizedlist> </sect2> |