A workaround for the difficulties of dealing with a contravariant 'In' parameter type...
A Rule is a function from some input to a Result.
A Rule is a function from some input to a Result. The result may be:
A factory for rules.
A factory for rules that apply to a particular context.
Represents the combined value of two rules applied in sequence.
Represents the combined value of two rules applied in sequence.
the Scala parser combinator