GuestLanguageEvaluator
A GuestLanguage feature for evaluating Source code in a given PolyglotContext.
Install an implementation of this interface using a PolyglotContextElement with a key obtained from GuestLanguageEvaluator.contextElementFor, with the target language as identifier, to intercept calls to PolyglotContext.evaluate.
PolyglotContext implementations will always prefer delegating execution to a GuestLanguageEvaluator for the relevant source if one is registered, falling back to their defaults if none is found.