as_json() returns a JSON string that carries the parsed object's public
R-side state and the raw compiler artifact JSON. saveRDS() / readRDS()
remains the primary persistence path for fitted objects; revive() restores
process-local caches after deserialization.
Usage
as_json(x, pretty = FALSE, ...)
# S3 method for class 'mm_compiled'
as_json(x, pretty = FALSE, ...)