docopt does not compile with ghc-8.8.2 #33
Description
[ 6 of 10] Compiling System.Console.Docopt.Public ( System/Console/Docopt/Public.hs, dist/build/System/Console/Docopt/Public.o )
System/Console/Docopt/Public.hs:195:17: error:
• Could not deduce (MonadFail m) arising from a use of ‘fail’
from the context: Monad m
bound by the type signature for:
getFirstArg :: forall (m :: * -> *).
Monad m =>
Arguments -> Option -> m String
at System/Console/Docopt/Public.hs:193:1-57
Possible fix:
add (MonadFail m) to the context of
the inferred type of failure :: m a
or the type signature for:
getFirstArg :: forall (m :: * -> *).
Monad m =>
Arguments -> Option -> m String
• In the expression: fail $ "no argument given: " ++ show opt
In an equation for ‘failure’:
failure = fail $ "no argument given: " ++ show opt
In the expression:
let failure = fail $ "no argument given: " ++ show opt
in
case opt `M.lookup` args of
Nothing -> failure
Just val
-> case val of
MultiValue vs -> ...
Value v -> return v
_ -> failure
|
195 | let failure = fail $ "no argument given: " ++ show opt
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[ 7 of 10] Compiling System.Console.Docopt.UsageParse ( System/Console/Docopt/UsageParse.hs, dist/build/System/Console/Docopt/UsageParse.o )
System/Console/Docopt/UsageParse.hs:7:1: warning: [-Wunused-imports]
The import of ‘dropWhile’ from module ‘Data.List’ is redundant
|
7 | import Data.List (nub, sortBy, maximumBy, dropWhile, dropWhileEnd)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[ 8 of 10] Compiling System.Console.Docopt.QQ ( System/Console/Docopt/QQ.hs, dist/build/System/Console/Docopt/QQ.o )
System/Console/Docopt/QQ.hs:59:25: error:
• No instance for (MonadFail ((->) String))
arising from a use of ‘fail’
• In the first argument of ‘(.)’, namely ‘fail’
In the expression: fail . (++ " context unsupported")
In an equation for ‘unsupported’:
unsupported = fail . (++ " context unsupported")
|
59 | where unsupported = fail . (++ " context unsupported")
| ^^^^