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Resolving dependencies...
Starting     RSolve-0.1.0.0
Building     RSolve-0.1.0.0
Failed to install RSolve-0.1.0.0
Build log ( /home/builder/.cabal/logs/ghc-8.6.1/RSolve-0.1.0.0-7Bb59rv6FuQHdN5m7YKGvL.log ):
cabal: Entering directory '/tmp/cabal-tmp-22292/RSolve-0.1.0.0'
Configuring RSolve-0.1.0.0...
Preprocessing library for RSolve-0.1.0.0..
Building library for RSolve-0.1.0.0..
[1 of 5] Compiling RSolve.BrMonad   ( src/RSolve/BrMonad.hs, dist/build/RSolve/BrMonad.o )
[2 of 5] Compiling RSolve.Infr      ( src/RSolve/Infr.hs, dist/build/RSolve/Infr.o )
[3 of 5] Compiling RSolve.Logic     ( src/RSolve/Logic.hs, dist/build/RSolve/Logic.o )
[4 of 5] Compiling RSolve.HM.Core   ( src/RSolve/HM/Core.hs, dist/build/RSolve/HM/Core.o )
[5 of 5] Compiling RSolve.Options.Core ( src/RSolve/Options/Core.hs, dist/build/RSolve/Options/Core.o )

src/RSolve/Options/Core.hs:61:5: error:
    • No instance for (Control.Monad.Fail.MonadFail (Br (LState Term)))
        arising from a do statement
        with the failable pattern ‘(r, Just rxs)’
    • In a stmt of a 'do' block: (r, Just rxs) <- pruneSol r
      In the expression:
        do (l, Just lxs) <- pruneSol l
           (r, Just rxs) <- pruneSol r
           case (S.size lxs, S.size rxs) of
             (1, 1) | lxs == rxs -> empty
             (1, 1) | lxs /= rxs -> return ()
             (nl, nr) | nl < nr -> complement (Var r) (Var l)
             (nl, nr) | nl >= nr -> do ...
      In an equation for ‘complement’:
          complement l r
            = do (l, Just lxs) <- pruneSol l
                 (r, Just rxs) <- pruneSol r
                 case (S.size lxs, S.size rxs) of
                   (1, 1) | lxs == rxs -> empty
                   (1, 1) | lxs /= rxs -> return ()
                   (nl, nr) | nl < nr -> complement (Var r) (Var l)
                   (nl, nr) | nl >= nr -> ...
   |
61 |     (r, Just rxs) <- pruneSol r
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
cabal: Leaving directory '/tmp/cabal-tmp-22292/RSolve-0.1.0.0'
cabal: Error: some packages failed to install:
RSolve-0.1.0.0-7Bb59rv6FuQHdN5m7YKGvL failed during the building phase. The
exception was:
ExitFailure 1