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@ihb2032 ihb2032 released this 09 Jun 08:46
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v0.3.0
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MoonFrame v0.3.0 — Release Notes

MoonFrame v0.3.0 grows the library's user-facing output surface, completes the join matrix, and adds engineering depth with a pluggable column-storage backend — all on top of the v0.2 method-chain core. Pre-1.0, breaking changes ride the minor version (see Breaking changes).

Highlights

  • HTML & Vega-Lite export — render a frame as a styled <table> or a Vega-Lite v5 chart spec you can paste straight into the Vega editor.
  • Full join matrix — right / outer complete the inner / left / right / outer / cross set.
  • Read resilience — the CSV / JSON / NDJSON readers gained escape hatches for messy, real-world data.
  • Pluggable column storage — an all-valid Numeric fast path alongside the general-purpose Arrow Builtin column, behind a closed ColumnStorage seam.
  • Faster group-by / join and O(1) slicing under the hood.

What's new

Output formats

  • DataFrame::to_html() / to_html_with_options(...) — a pure, dependency-free renderer (CSS class, <caption>, a max_rows cap, and HTML escaping by default), parallel to to_markdown.
  • format_vega_lite(df, spec) / write_vega_lite(...) — a complete Vega-Lite v5 spec ($schema + mark + encoding + inline data.values). ChartSpec::bar / line / point / area, with with_color / with_title.

Join — Right / Outer

JoinType gained Right and Outer, completing the matrix, with right_join / outer_join convenience methods and Polars-aligned semantics (null keys match nothing; NaN keys match; per-how coalesce defaults, overridable with with_coalesce).

Read resilience

infer_schema_rows = 0 scans every row instead of a leading window; on_parse_error (Raise / Null) chooses whether an off-type cell past the window fails the read or downgrades to null; CSV's allow_nonfinite_floats controls whether nan / inf tokens infer as Float or fall back to String.

Pluggable column storage

A Series now holds a ColumnStorage — a closed { Builtin; Numeric } seam. Numeric is an all-valid, unboxed Int64 / Double column with no validity bitmap (the null_count == 0 fast path); from_ints / from_floats pick it automatically, and structural transforms keep a column on the fast path. storage_kind() / to_numeric() / to_builtin() inspect and convert.

Performance

  • group-by / join keys are now hashed on native cell values — no per-row string key, and no decimal-string round-trip for numeric keys.
  • Bitmap slicing is O(1) — head / tail / slice share the parent's validity buffer (a zero-copy view) instead of repacking it.

Breaking changes

Pre-1.0, breaking changes ride the minor version. The source-level breaks:

  • Series::storage() now returns @column.ColumnStorage (was @column.BuiltinColumn). The .data() / .validity() reading surface is unchanged, so column-reading call sites still compile; use .to_builtin() for the concrete BuiltinColumn.
  • Series::new(name, ...) takes a ColumnStorage (pass ColumnStorage::from_builtin(col), or use the unchanged Series::from_builtin).
  • JoinType gained Right / Outer — an exhaustive match over it must now handle the two new variants.
  • The CSV / JSON / NDJSON *ReadOptions structs gained pub(all) fields; a full struct literal must add them or switch to ::default() (the defaults reproduce the prior behaviour exactly).

Step-by-step upgrade notes are in migration.md.

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