Add equivalent of “important” blocks?

[LunaTheFoxgirl]

Add equivalent of “important” blocks?

[veelo]

I don't quite understand what you propose. Maybe you can start with a currently working example, and describe what you don't like about its behaviour. Note that {...} are reserved for semantic actions. Poor error messages are a known limitation of Pegged, error reporting is probably the hardest part of a parser generator.

[LunaTheFoxgirl]

I am unable to provide a "working example" at current time, but essentially what I want is a way to force pegged to stop parsing and output an error if a rule fails.
And yeah, I later realised that { and } are already taken.

But yeah, what I need is a way to tell pegged a way to halt parsing and display an error if a rule fails, without using semantic actions + throwing exceptions from that.

[veelo]

I think there is a way to get what you want using parser composition and semantic actions. So why wouldn't you want to use semantic actions?