Control.Monad.Prospect

Prospecting of free monads

prospect :: (Functor f, Generic1 f, GExplore f (Rep1 f)) => Free f a -> (Maybe a, [f ()])

Perform a best-effort analysis of a free monad by automatically exploreing it.

survey

Arguments

:: Functor f

=> (forall b. f (Free f b) -> Free f b)

The following function. Consider using explore to get an automatic implementation for this.

-> Free f a

-> (Maybe a, [f ()])

Perform a best-effort analysis of a free monad.

explore :: forall f a. (Generic1 f, GExplore f (Rep1 f)) => f a -> a

An automatically generated (and unsafe) f-algebra capable of tearing down any functor f with a Generic1 instance. explore will guess its way through any continuations it discovers.

Guesswork

guess :: a

A guess is a bottom whose evaluation can be caught by way of verify or given. It can be used to follow continuations in a free monad until it branches.

given :: Alternative f => (a -> f b) -> a -> f b

Strictly attempt a function application, returning empty if the argument was a guess.

verify :: Alternative f => a -> f a

Attempt to evaluate the pure value a, returning empty if it was a guess.

ensure :: (Alternative f, NFData a) => a -> f a

Like verify, but much stricter.

proceed :: (Alternative f, NFData a) => (a -> f b) -> a -> f b

Like given, but much stricter.

data Guess

The underlying machinery of guess.

Constructors

Guess

Instances

Eq Guess

Defined in Control.Monad.Prospect

Methods

(==) :: Guess -> Guess -> Bool

(/=) :: Guess -> Guess -> Bool

Show Guess

Defined in Control.Monad.Prospect

Methods

showsPrec :: Int -> Guess -> ShowS

show :: Guess -> String

showList :: [Guess] -> ShowS

Exception Guess

Defined in Control.Monad.Prospect

Methods

toException :: Guess -> SomeException

fromException :: SomeException -> Maybe Guess

displayException :: Guess -> String