# OCaml 5.3.0 — OCaml 5.3.0

- Product: OCaml (https://whatsnew.fyi/product/ocaml)
- Vendor: OCaml
- Date: 2025-01-08
- Version: 5.3.0
- Original notes: https://github.com/ocaml/ocaml/releases/tag/5.3.0
- Permalink: https://whatsnew.fyi/product/ocaml/releases/5.3.0

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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- **added** — Syntax for deep effect handlers
- **added** — Statistical memory profiling (statmemprof)
- **added** — UTF-8 encoded Unicode source files and support for Unicode identifiers
- **added** — Around 20 new functions in the standard library
- **changed** — More space-efficient implementation of Dynarray
- **changed** — Improved metadata on pairs of declarations and definitions for merlin
- **changed** — Improved error messages for first-class modules, functors, labeled arguments, and type clashes
- **fixed** — Restored MSVC port
- **fixed** — Many fixes and improvements in the runtime
- **fixed** — Numerous bug fixes

Some of the highlights in OCaml 5.3.0 are:

- Syntax for deep effect handlers
- Restored MSVC port
- Re-introduced statistical memory profiling (statmemprof)
- utf-8 encoded Unicode source files and modest support of Unicode identifiers
- More space-efficient implementation of Dynarray
- Improved metadata on the pairs of declarations and definitions for merlin.

And a lot of incremental changes:

- Around 20 new functions in the standard library
- Many fixes and improvements in the runtime
- Improved error messages for first-class modules, functors, labeled arguments,
type clashes.
- Numerous bug fixes