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| author | Ian Lynagh <igloo@earth.li> | 2012-01-14 13:40:58 +0000 |
|---|---|---|
| committer | Ian Lynagh <igloo@earth.li> | 2012-01-14 13:46:11 +0000 |
| commit | 57b1d54a56b406648dd198092419441b990b3ae1 (patch) | |
| tree | 44db7a9245fc19f8e81285a156268e60d5a9cc51 | |
| parent | 804108f0c0fbc2c5f926e4cb4d30b3891443a079 (diff) | |
| download | haskell-57b1d54a56b406648dd198092419441b990b3ae1.tar.gz | |
Document the Num superclass divergence from H98/H2010
| -rw-r--r-- | docs/users_guide/bugs.xml | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/docs/users_guide/bugs.xml b/docs/users_guide/bugs.xml index 12ef9460da..9da7927bc9 100644 --- a/docs/users_guide/bugs.xml +++ b/docs/users_guide/bugs.xml @@ -150,6 +150,39 @@ main = do args <- getArgs <variablelist> <varlistentry> + <term>Num superclasses</term> + <listitem> + <para> + The <literal>Num</literal> class does not have + <literal>Show</literal> or <literal>Eq</literal> + superclasses. + </para> + + <para> + You can make code that works with both + Haskell98/Haskell2010 and GHC by: + <itemizedlist> + <listitem> + <para> + Whenever you make a <literal>Num</literal> instance + of a type, also make <literal>Show</literal> and + <literal>Eq</literal> instances, and + </para> + </listitem> + <listitem> + <para> + Whenever you give a function, instance or class a + <literal>Num t</literal> constraint, also give it + <literal>Show t</literal> and + <literal>Eq t</literal> constraints. + </para> + </listitem> + </itemizedlist> + </para> + </listitem> + </varlistentry> + + <varlistentry> <term>Multiply-defined array elements—not checked:</term> <listitem> <para>This code fragment should |