Fix building with Template Haskell 2.18 / GHC 9.2. #1716
Conversation
| @@ -206,12 +206,12 @@ instance MonadTrans (ResultT a) where | |||
| instance (MonadIO m, Error a) => MonadIO (ResultT a m) where | |||
| liftIO = ResultT . liftIO | |||
| . liftM (either (failError . show) return) | |||
| . (try :: IO a -> IO (Either IOError a)) | |||
| . (try :: IO α -> IO (Either IOError α)) | |||
There was a problem hiding this comment.
Sorry for being late.
What has changed here? Latin letter a to Greek letter α (alpha)? Is this intentional? And if so, why?
There was a problem hiding this comment.
This is presumably to decouple the inner (IO a) from the outer (Error a) type, letting type inference do its magic. @mbakke Greek letters are great (obviously, I'm Greek :-) but it's rather unusual to encounter them in source code. I would stick with ASCII characters if possible, e.g. we could try using a' here.
| @@ -206,12 +206,12 @@ instance MonadTrans (ResultT a) where | |||
| instance (MonadIO m, Error a) => MonadIO (ResultT a m) where | |||
| liftIO = ResultT . liftIO | |||
| . liftM (either (failError . show) return) | |||
| . (try :: IO a -> IO (Either IOError a)) | |||
| . (try :: IO α -> IO (Either IOError α)) | |||
There was a problem hiding this comment.
This is presumably to decouple the inner (IO a) from the outer (Error a) type, letting type inference do its magic. @mbakke Greek letters are great (obviously, I'm Greek :-) but it's rather unusual to encounter them in source code. I would stick with ASCII characters if possible, e.g. we could try using a' here.
|
|
||
| instance (MonadBase IO m, Error a) => MonadBase IO (ResultT a m) where | ||
| liftBase = ResultT . liftBase | ||
| . liftM (either (failError . show) return) | ||
| . (try :: IO a -> IO (Either IOError a)) | ||
| . (try :: IO α -> IO (Either IOError α)) |
Hello,
Here is another hack similar to #1694 that fixes building with GHC 9.2 simply by commenting type signatures. Also introduce a
myConPfor backwards compatibility with Template Haskell < 2.18.CC @apoikos .