found that sogaiu replaced default-peg-grammar with (dyn :peg-grammar). This change broke peg/compile.

Perhaps you wouldn't mind indicating the specifics?

Ouch. I discovered that bakpakin replaced default-peg-grammar with (dyn :peg-grammar) in 85155bb.

I was careless in monkey mode.

Thanks for the details.

Errors happen. No harm done.

FWIW, according to the commit message for 85155bb, the change in question was allegedly part of activity supporting this endeavor.

Note that this change has been in place for just about 5 years (from 2021-01-24).

Perhaps, default-peg-grammar should become immutable? You can change (dyn :peg-grammar) even if default-peg-grammar is immutable.

@bakpakin Should default-peg-grammar become a struct instead of a table? #478 can be an outdated optimization at this point.

We can avoid loading the full core environment if the mutable parts of core are not reachable from the main function.

It seems to me that you don't really need to modify default-peg-grammar during runtime.... In practice, people just want the default. If people wanted more shared grammar, then they can carry it outside default-peg-grammar. This is also certainly more functional and referentially transparent. I decrease complexity by sticking to referential transparency unless I have to deviate from it.

Or, perhaps this pull request is good enough because most small scripts don't launch a new thread....

There was some concern originally about accidentally pulling in the entire core library just to compile PEGs, but I think that is not a realistic problem for most users - the current architecture was originally done to decouple Pegs from core. There are plenty of ways to optimize this but I think this is the simplest solution for now.

In practice, people just want the default. If people wanted more shared grammar, then they can carry it outside default-peg-grammar.

FWIW, I've added to default-peg-grammar before. That lets you provide things to more than one grammar by only making changes in one place.

Hmm, I just realized some other issues with this change, perhaps I merged too soon. Let me test some stuff locally, but I think may want to revert this. Sorry @amano-kenji