Signatures for the dependencies used in Sugar's module builders.
module type Monad = sig ... endA generic signature describing a monad.
module type Error = sig ... endConventional module type to define the errors inside a project. This is how Sugar understands the error handling layer of a project.
module type Strict_error = sig ... endThis signature describes an Error module that has some control over unexpected exceptions.
module type Strict_monad = sig ... endA monad that provides some awareness about unexpected exceptions.