FEATURE: Collection Transformation Builtins

Workflow

Collection filters transform arrays, objects, and nested values while preserving jq stream ordering and multiplicity. Implement map, map_values, select, add, flatten, transpose, combinations, and walk, including empty streams, bounded flattening, recursive traversal, and immutable updates.

Programmatic Acceptance

=== AC data-001-conformance ===
Intent: The collection transformation slice executes matching corpus cases and passes all selected cases.
Suite: scoped
Requires: executable=python3; scope=test

import json import os import subprocess import sys

select = r"map|flatten|transpose|combinations|walk" result = subprocess.run( [sys.executable, "sources/run_conformance.py", "--select", select, "--json"], capture_output=True, text=True, env={**os.environ, "JQ": f"{os.getcwd()}/jq"}, ) print(result.stdout) print(result.stderr, file=sys.stderr) report = json.loads(result.stdout) summary = report["summary"] assert sum(summary.values()) > 0 assert summary["fail"] == 0 assert summary["error"] == 0 assert result.returncode == 0 === END AC data-001-conformance ===

User Acceptance

• None.

Guardrails

• Preserve generator ordering, multiplicity, backtracking, and immutable-value semantics.
• Use only Python standard-library facilities.