// Package engine defines a general process of reducing a lambda calculus
// expression.
package engine

// A Process handles the reduction of a single expression.
type Process[T any] interface {
	// Get the current state of the process.
	// Returns an error if the current state cannot be represented.
	Get() (T, error)

	// Step performs reduction(s) on the representation. If the number of steps
	// defined is less than zero, it will perform as many reductions as
	// possible. Returns whether a reduction was performed.
	Step(int) bool
}

// An Engine is an function that generates reduction processes.
type Engine[T any] = func(T) (Process[T], error)