Data.OpenWitness

Documentation

data OpenWitness s a

A witness type that can witness to any type. But values cannot be constructed; they can only be generated in IO and certain other monads.

Instances

TestEquality k (OpenWitness k k s)

Eq (OpenWitness k k s a)

data RealWorld

The s type for running OW in IO.

type IOWitness = OpenWitness RealWorld

An OpenWitness for IO.

newIOWitness :: forall a. IO (IOWitness a)

Generate a new IOWitness in IO.

data OW s a

A runnable monad in which OpenWitness values can be generated. The s parameter plays the same role as it does in ST, preventing OpenWitness values from one run being used in another.

Instances

Monad (OW k s)

Functor (OW k s)

MonadFix (OW k s)

Applicative (OW k s)

newOpenWitnessOW :: forall s a. OW s (OpenWitness s a)

Generate a new OpenWitness in OW.

runOW :: forall a. (forall s. OW s a) -> a

Run an OW computation.

owToIO :: OW RealWorld a -> IO a

Run an OW computation in IO.

iowitness :: TypeQ -> Q Exp

Template Haskell function to declare IOWitness values.