Panic when printing out kind incompatibility error
I wrote a little utility function against the new pipes 4.0 repository but neglected to put the brackets around lift (f x)
like so:
mapM :: (Monad m) => (a -> m b) -> Pipe a b m r
mapM f = for cat $ \x -> do
r <- lift f x
yield r
Which resulted in this error/panic.
src/Utils/Pipes.hs:13:8:
Couldn't match kind `* -> *' with `*'
Expected type: a -> Proxy () a () b m b
Actual type: a -> Proxy () a () b m b
Kind incompatibility when matching types:
a :: * -> *
a :: *
The function `lift'ghc: panic! (the 'impossible' happened)
(GHC version 7.6.2 for x86_64-unknown-linux):
kindFunResult ghc-prim:GHC.Prim.*{(w) tc 34d}