Resumable parsing using continuation primitives

So far, resumable parsers were really only feasible with CPS-based internals, like in Attoparsec. Unfortunately, that has painful overhead because it effectively moves the control stack of the parsers to the heap, and continuation closure calls are also slower than native GHC returns.

GHC 9.6.x is now available in release candidates, and it has new primops for delimited continuations: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0313-delimited-continuation-primops.rst It might be interesting to investigate the new primitives. The idea would be to save the current parser continuation when running out of input, instead of throwing an error.

Start by reading the linked GHC proposal on delimited continuation primops and the existing resumable-parser approach described in the issue. Determine how parser continuation state is currently represented and what would need to change to preserve it on input exhaustion. Done would require a defined implementation and evidence that resumable parsing works with the new primitives.