25. Discarding Separators in the Example Grammars

• Counting the nodes allocated against those in the final tree showed that about half of the JSON parser's nodes were thrown away. Among them, every element after the first in rest:(-ws "," -ws m:member)* kept the "," as a Match child of the iteration's Seq (a captured repetition keeps its whole CST, see the guideline below): 15,550 nodes per parse in JSON and 25,005 in CSV. The JSON, CSV and minilang examples now discard the separator (-","); the ASTs are unchanged.
• The rest of the discarded nodes are the iteration Seq nodes themselves and intermediate lists built by list, map and concat in actions.
• Effect (min of 6 runs alternating the old and new grammars, Apple M3 Max, code points): bytes per parse JSON 25.8 → 23.6 MB, CSV 22.5 → 19.0 MB, minilang 18.9 → 18.6 MB (closure); CSV 3.5% faster on the closure and bytecode backends, JSON and minilang unchanged within noise. Generated parsers: JSON 11.2 → 10.9 ms, CSV 5.5 → 5.2 ms.