Control.Monad.Operational

A reconstruction of the operational package in terms of the FreeT monad transformer.

This module is meant to be a drop-in replacement for its counterpart in the operational package. Some of the implementation choices reflect that:

• Program instr and ProgramView instr are type synonyms for ProgramT instr m and ProgramViewT instr m, just as in operational. If you don't care for that, Control.Monad.Operational.Simple implements them directly in terms of Free.

The ProgramT and ProgramViewT types and operations are reexported from Control.Monad.Trans.Operational.

Documentation

module Control.Operational.Class

module Control.Monad.Trans.Operational

type Program instr = ProgramT instr Identity

Drop-in replacement for operational's type synonym.

toFree :: Program instr a -> Free (Yoneda instr) a

The Free monad action for a Program.

fromProgram :: (Operational instr m, Functor m, Monad m) => Program instr a -> m a

Lift a Program into any Operational type at least as strong as Monad.

liftProgram :: Monad m => Program instr a -> ProgramT instr m a

Lift a Program into a ProgramT. Really the same as fromProgram, but with a more restricted type; this function is a drop-in replacement for the eponymous function in operational.

interpret :: forall m instr a. (Functor m, Monad m) => (forall x. instr x -> m x) -> Program instr a -> m a

Interpret a Program by interpreting each instruction as a monadic action. Unlike interpretWithMonad, this soes not use view nor ProgramView.

This function is not a drop-in replacement for interpretWithMonad because it has an extra Functor m constraint.

interpretWithMonad :: Monad m => (forall x. instr x -> m x) -> Program instr a -> m a

Drop-in replacement for the eponymous function in the operational package. This is like interpret but with a slightly broader type, and the same implementation as in operational (in terms of view).

type ProgramView instr = ProgramViewT instr Identity

Drop-in replacement for operational's eponymous type synonym.

view :: Program instr a -> ProgramView instr a

Drop-in replacement for operational's function.