Document AMP as a Report deviation

`Applicative` as a superclass of `Monad` is non-standard.

Fixes #13196.

[skip ci]

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D3185

1 files changed, 7 insertions, 2 deletions

diff --git a/docs/users_guide/bugs.rst b/docs/users_guide/bugs.rst
index 9b60e5429c..707f66b4ec 100644
--- a/docs/users_guide/bugs.rst
+++ b/docs/users_guide/bugs.rst
@@ -213,8 +213,8 @@ Numbers, basic types, and built-in classes
     -  Whenever you give a function, instance or class a ``Num t``
         constraint, also give it ``Show t`` and ``Eq t`` constraints.
 
-``Bits`` superclasses
-    The ``Bits`` class does not have a ``Num`` superclasses. It
+``Bits`` superclass
+    The ``Bits`` class does not have a ``Num`` superclass. It
     therefore does not have default methods for the ``bit``, ``testBit``
     and ``popCount`` methods.
 
@@ -239,6 +239,11 @@ Numbers, basic types, and built-in classes
     extra methods simply because ``ReadPrec`` is more efficient than ``ReadS``
     (the type on which ``readsPrec`` is based).
 
+``Monad`` superclass
+    The ``Monad`` class has an ``Applicative`` superclass. You cannot write
+    ``Monad`` instances that work for GHC and also for a Haskell 2010
+    implementation that does not define ``Applicative``.
+
 Extra instances
     The following extra instances are defined: ::