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Won't compile; problem with coercion of msplit #2

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JeffreyBenjaminBrown opened this issue Nov 20, 2017 · 1 comment
Open

Won't compile; problem with coercion of msplit #2

JeffreyBenjaminBrown opened this issue Nov 20, 2017 · 1 comment

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@JeffreyBenjaminBrown
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jeff@jbb-lenovo:~/code/logic/MiniKanrenT$ stack init
Looking for .cabal or package.yaml files to use to init the project.
Using cabal packages:
- MiniKanrenT.cabal

Selecting the best among 11 snapshots...

* Matches lts-9.14

Selected resolver: lts-9.14
Initialising configuration using resolver: lts-9.14
Total number of user packages considered: 1
Writing configuration to file: stack.yaml
All done.
jeff@jbb-lenovo:~/code/logic/MiniKanrenT$ stack ghci
MiniKanrenT-0.0.1: configure (lib)
Configuring MiniKanrenT-0.0.1...
MiniKanrenT-0.0.1: initial-build-steps (lib)
Configuring GHCi with the following packages: MiniKanrenT
GHCi, version 8.0.2: http://www.haskell.org/ghc/  :? for help
[1 of 4] Compiling Control.Monad.LogicVarT ( /home/jeff/code/logic/MiniKanrenT/src/Control/Monad/LogicVarT.hs, interpreted )

/home/jeff/code/logic/MiniKanrenT/src/Control/Monad/LogicVarT.hs:57:55: error:
    • Couldn't match representation of type ‘m (Maybe
                                                  (a, LogicVarT m a),
                                                LVarData)’
                               with that of ‘m (Maybe (a, StateT LVarData m a), LVarData)’
        arising from the coercion of the method ‘msplit’
          from type ‘forall a.
                     StateT LVarData m a
                     -> StateT LVarData m (Maybe (a, StateT LVarData m a))’
            to type ‘forall a.
                     LogicVarT m a -> LogicVarT m (Maybe (a, LogicVarT m a))’
      NB: We cannot know what roles the parameters to ‘m’ have;
        we must assume that the role is nominal
    • When deriving the instance for (MonadLogic (LogicVarT m))
Failed, modules loaded: none.
@aullenverch130
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aullenverch130 commented Mar 20, 2022

Has anybody solved this issue? I tried to compile with the same result.

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