140: LIST_VALUE's copy reviewed before building (measured by spec: UAX #14 about 10% of its time, JSON tree 6%, HTTP 2%, inflate 0.06%, the rest none; the cost a tree built item by item, 64 ns an item and 250 ns a copy): lend and detach (CoW) noted as the decision point (a branch on every event list's change for 10/6/2/0/0/0), a compile-time move ruled out (it changes LIST_VALUE's contract), the arrays copied whole built (UAX #14 -6.8%, its share to about 3%); 041's five works within 0.03% (b49, b50), the bank's queries within 0.3% (s49, s50), noise between builds larger

1 files changed, 8 insertions, 0 deletions

diff --git a/research/experiments/044-specs/2026-10-19-list-value.jsonl b/research/experiments/044-specs/2026-10-19-list-value.jsonl
new file mode 100644
index 0000000..c5058c2
--- /dev/null
+++ b/research/experiments/044-specs/2026-10-19-list-value.jsonl
@@ -0,0 +1,8 @@
+{"what": "list values by spec, before (an instrumented build, not committed: nest() timed; ROUNDS 1, 8 passes)", "pure_jit": "0", "linebreak": {"list_values": 1344384, "items": 4412520, "ns": 485793268, "passes": 8, "source_form": "FLAT"}, "json_tree": {"list_values": 32008, "items": 96000, "ns": 35799925, "passes": 8, "source_form": "tree"}, "http": {"list_values": 4768, "items": 16536, "ns": 4182491, "passes": 8, "source_form": "tree"}, "inflate": {"list_values": 72, "items": 4312, "ns": 302150, "passes": 8}, "dns": {"list_values": 0}, "json": {"list_values": 0}, "layout": {"list_values": 0}}
+{"what": "a list value of numbers, ns a copy (instrumented, its clock in it: 100-150 ns)", "items": [3, 60, 600], "before": [540, 3926, 38268], "after": [320, 324, 985]}
+{"what": "linebreak nest() a pass, ns (instrumented)", "before": 48646023, "after": 17293018, "copies": 168048}
+{"what": "time, base (f1bb9de) and new (1c1133c) libpure, three pairs in turns, medians", "spec": "linebreak", "pure_jit": "0", "base": {"ns": 6916.7, "runs": [6956.2, 6914.4, 6916.7], "instructions": 1774.3}, "new": {"ns": 6444.7, "runs": [6445.9, 6437.0, 6444.7], "instructions": 1774.3}}
+{"what": "time, base (f1bb9de) and new (1c1133c) libpure, three pairs in turns, medians", "spec": "json_tree", "pure_jit": "0", "base": {"ns": 606.014, "runs": [606.014, 605.443, 606.019], "instructions": 248.0}, "new": {"ns": 607.423, "runs": [608.203, 607.423, 606.024], "instructions": 248.0}}
+{"what": "time, base (f1bb9de) and new (1c1133c) libpure, three pairs in turns, medians", "spec": "http", "pure_jit": "0", "base": {"ns": 270.569, "runs": [270.569, 270.789, 270.399], "instructions": 61.6}, "new": {"ns": 270.517, "runs": [270.613, 270.517, 270.509], "instructions": 61.6}}
+{"what": "time, base (f1bb9de) and new (1c1133c) libpure, three pairs in turns, medians", "spec": "inflate", "pure_jit": "0", "base": {"ns": 894.96, "runs": [894.96, 894.952, 894.965], "instructions": 151.2}, "new": {"ns": 895.166, "runs": [895.166, 895.338, 894.811], "instructions": 151.2}}
+{"what": "041's five works, user-mode instructions of 3 rounds (041-batches/2026-10-19-counts.jsonl)", "b49 batches bfs": 3341464590, "b49 rounds bfs": 4704847479, "b49 batches join": 1783721471, "b49 rounds join": 7711078090, "b49 batches knapsack": 348032921, "b49 rounds knapsack": 22068882218, "b49 batches matmul": 702231807, "b49 rounds matmul": 21188570525, "b49 batches roots": 157246650, "b49 rounds roots": 2715504255, "b50 batches bfs": 3341464219, "b50 rounds bfs": 4704848617, "b50 batches join": 1783747800, "b50 rounds join": 7711078484, "b50 batches knapsack": 348113595, "b50 rounds knapsack": 22068882244, "b50 batches matmul": 702235577, "b50 rounds matmul": 21188570749, "b50 batches roots": 157246595, "b50 rounds roots": 2715504257}