refactor(crypto): use itertools.batched in merkleize pair-walk#966
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tcoratger merged 1 commit intoJun 12, 2026
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Replace the manual index-stepping pair iteration with itertools.batched, the established idiom across the xmss crypto modules. An odd tail surfaces as a length-one tuple, where the missing right sibling is filled with the all-zero subtree root, preserving the exact zero-padding behavior of the previous code. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
The
merkleizepair-walk insrc/lean_spec/spec/crypto/merkleization.pystepped a manual index over each tree level to pull left and right siblings. This replaces that hand-rolled loop withitertools.batched(level, 2), the idiom already used across the xmss crypto modules (merkle.py,prf.py,poseidon.py).An odd tail surfaces as a length-one tuple, exactly where the previous
elsebranch fired. The missing right sibling is still filled with the all-zero subtree root, so the zero-padding behavior is unchanged.Behavior
Behavior-preserving. No new tests; all 105 existing tests in
tests/spec/crypto/test_merkleization.pypass.Checks
just checkpasses (ruff, ruff format, ty, codespell, mdformat).🤖 Generated with Claude Code