Using lift with StateT and Maybe on GHCI
I was playing around with StateT
and Maybe
today and I run the following two commands (consider that TC
== import qualified Control.Monad.Trans.Class as TC
:
ghci> let g = TC.lift Just [3, 4] :: StateT [Int] Maybe Int
which led to a:
<interactive>:54:9:
Couldn't match kind `* -> *' with `*'
Expected type: [t0] -> StateT [Int] Maybe Int
Actual type: [t0] -> StateT [Int] Maybe Int
Kind incompatibility when matching types:
[t_i] :: * -> *
[t0] :: *
The function `TC.lift'ghc: panic! (the 'impossible' happened)
(GHC version 7.6.3 for x86_64-apple-darwin):
kindFunResult
<<details unavailable>>
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
and
> let g = TC.lift Just (1, [3, 4]) :: StateT [Int] Maybe Int
which led to:
<interactive>:55:9:
Couldn't match kind `* -> *' with `*'
Expected type: (t0, [t1]) -> StateT [Int] Maybe Int
Actual type: (t0, [t1]) -> StateT [Int] Maybe Int
Kind incompatibility when matching types:
(t_i, [t_l]) :: * -> *
(t0, [t1]) :: *
The function `TC.lift'ghc: panic! (the 'impossible' happened)
(GHC version 7.6.3 for x86_64-apple-darwin):
kindFunResult
<<details unavailable>>
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
I'm just doing what the last line asked me. :)
Trac metadata
Trac field | Value |
---|---|
Version | 7.6.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | low |
Resolution | Unresolved |
Component | GHCi |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | hvr |
Operating system | |
Architecture |