# OCaml 5.1.1 — OCaml 5.1.1

- Product: OCaml (https://whatsnew.fyi/product/ocaml)
- Vendor: OCaml
- Date: 2023-12-07
- Version: 5.1.1
- Original notes: https://github.com/ocaml/ocaml/releases/tag/5.1.1
- Permalink: https://whatsnew.fyi/product/ocaml/releases/5.1.1

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **removed** — Remove Marshal.Compression module, compressed marshaling has been moved to an internal compiler library

- Breaking change: `Marshal.Compression` has been removed, compressed marshaling has been moved to an internal compiler library
- Bug fixes. See [detailed list of changes](https://github.com/ocaml/ocaml/blob/5.1/Changes).