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Release 7.4.3 introduces breaking API changes #7
Description
Pinging @gbaz, as this was discovered in jmacro-rpc-happstack breakage. Version 7.4.3 of happstack-server introduces the following API breakage at a few places:
-instance (Monad m) => Monoid (ServerPartT m a) where
+instance (Monad m, MonadPlus m) => Monoid (ServerPartT m a) whereThis leads to downstream packages no longer compiling, e.g.:
Network/JMacroRPC/Happstack.hs:101:55:
Could not deduce (Control.Monad.MonadPlus m)
arising from a use of ‘mappend’
from the context (Monad m, Functor m, MonadIO m)
bound by the type signature for
panelToPage :: (Monad m, Functor m, MonadIO m) =>
Maybe String
-> String -> Panel (ServerPartT m) -> ServerPartT m Response
at Network/JMacroRPC/Happstack.hs:100:16-123
Possible fix:
add (Control.Monad.MonadPlus m) to the context of
the type signature for
panelToPage :: (Monad m, Functor m, MonadIO m) =>
Maybe String
-> String -> Panel (ServerPartT m) -> ServerPartT m Response
In the expression: dir "jrpcs" updateHandler `mappend` drawHandler
In an equation for ‘panelToPage’:
panelToPage jqLoc title p
= dir "jrpcs" updateHandler `mappend` drawHandler
where
(updateHandler, drawHandler)
= panelToPageGen
(serveRpcs $ const (return ()))
(return . toResponse . H.preEscapedToHtml)
jqLoc
title
p
This change requires a major version bump. I'll need to temporarily block version 7.4.3 from Stackage until either the problem is resolved or downstream packages update to require the MonadPlus constraint as well.
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