Compatibility with mtl-2.3

[sjakobi]

operational will need code changes:

Building library for operational-0.2.4.1..
[1 of 1] Compiling Control.Monad.Operational ( src/Control/Monad/Operational.hs, dist/build/Control/Monad/Operational.o, dist/build/Control/Monad/Operational.dyn_o )

src/Control/Monad/Operational.hs:213:14: error:
    • Variable not in scope:
        liftM :: (a -> b) -> ProgramT instr m a -> ProgramT instr m b
    • Perhaps you meant ‘lift’ (imported from Control.Monad.Trans)
    |
213 |     fmap   = liftM
    |              ^^^^^

src/Control/Monad/Operational.hs:217:14: error:
    • Variable not in scope:
        ap
          :: ProgramT instr m (a -> b)
             -> ProgramT instr m a -> ProgramT instr m b
    • Perhaps you meant ‘map’ (imported from Prelude)
    |
217 |     (<*>)  = ap
    |              ^^

src/Control/Monad/Operational.hs:243:13: error:
    • Variable not in scope:
        ap
          :: ProgramViewT instr m (a -> b)
             -> ProgramViewT instr m a -> ProgramViewT instr m b
    • Perhaps you meant ‘map’ (imported from Prelude)
    |
243 |     (<*>) = ap
    |             ^^

src/Control/Monad/Operational.hs:248:54: error:
    • Variable not in scope:
        (>=>)
          :: (b1 -> ProgramT instr m a)
             -> (a -> ProgramT instr m b) -> b1 -> ProgramT instr m b
    • Perhaps you meant one of these:
        ‘>>=’ (imported from Prelude), ‘>>’ (imported from Prelude),
        ‘>=’ (imported from Prelude)
    |
248 |     (instr :>>= cont1) >>= cont2 = instr :>>= (cont1 >=> unviewT . cont2)
    |                                                      ^^^

[HeinrichApfelmus]

Thanks for reporting!

Apparently, mtl-2.3 has now been deprecated, though. 🤔

https://hackage.haskell.org/package/mtl/preferred

Looks like this can be postponed.

[HeinrichApfelmus]

Superseded by #33