Update to lts-12.10, support ghc 8.4, and aeson 1.3.

Don't fully understand the need for the MonoLocalBinds language extension,
which was not needed before but now ghc complains if it's not included,
but I've tested it and it does work.

All the rest of the changes are straightforward AMP changes and dep
updates.

Removed fgl from stack.yaml because it seems that indirect dep no longer
needs to be specified for stack to build.

Added custom-setup stanza since stack now warns without one.

This commit was sponsored by Trenton Cronholm on Patreon.

1 files changed, 2 insertions, 1 deletions

diff --git a/WebSockets.hs b/WebSockets.hs
index c2fcb95..7a53c8c 100644
--- a/WebSockets.hs
+++ b/WebSockets.hs
@@ -40,12 +40,13 @@ import qualified Data.Serialize
 import qualified Data.Text as T
 import qualified Data.ByteString.Lazy as L
 import Data.List
-import Data.Monoid
 import Data.Maybe
 import Text.Read
 import Control.Monad
 import Network.URI
 import System.IO
+import Data.Monoid
+import Prelude
 
 -- | Framing protocol used over a websocket connection.
 --