Make Applicative a superclass of Monad

Summary:
This includes pretty much all the changes needed to make `Applicative`
a superclass of `Monad` finally. There's mostly reshuffling in the
interests of avoid orphans and boot files, but luckily we can resolve
all of them, pretty much. The only catch was that
Alternative/MonadPlus also had to go into Prelude to avoid this.

As a result, we must update the hsc2hs and haddock submodules.

Signed-off-by: Austin Seipp <austin@well-typed.com>

Test Plan: Build things, they might not explode horribly.

Reviewers: hvr, simonmar

Subscribers: simonmar

Differential Revision: https://phabricator.haskell.org/D13

1 files changed, 11 insertions, 0 deletions

diff --git a/libraries/base/Data/Proxy.hs b/libraries/base/Data/Proxy.hs
index ab89066cfa..38a43b0b0f 100644
--- a/libraries/base/Data/Proxy.hs
+++ b/libraries/base/Data/Proxy.hs
@@ -69,10 +69,21 @@ instance Bounded (Proxy s) where
     minBound = Proxy
     maxBound = Proxy
 
+instance Monoid (Proxy s) where
+    mempty = Proxy
+    mappend _ _ = Proxy
+    mconcat _ = Proxy
+
 instance Functor Proxy where
     fmap _ _ = Proxy
     {-# INLINE fmap #-}
 
+instance Applicative Proxy where
+    pure _ = Proxy
+    {-# INLINE pure #-}
+    _ <*> _ = Proxy
+    {-# INLINE (<*>) #-}
+
 instance Monad Proxy where
     return _ = Proxy
     {-# INLINE return #-}