evaluator

type Comparator interface {
	// Compare performs an comparison by giving a set of variables.
	Compare(Variables) (bool, error)

	fmt.Stringer
}

type Evaluator interface {
	// Eval performs an evaluation by giving a set of variables.
	Eval(Variables) (interface{}, error)

	//Strict sets the expression evaluation to run in strict mode. The default is false.
	//For example, the behavior changes when the variable is not set.
	//  Referenced as nil if Strict is set to false.
	//  If set to true, the expression evaluation will be Error.
	Strict(bool)

	// AsComparator attempts to convert to Comparator
	AsComparator() (Comparator, bool)

	fmt.Stringer
}

type NumOfArgumentsMismatchError struct {
	FunctionName string
	Expected     int
	Given        int
}

type Variables map[string]interface{}