There's a crucial distinction! OCaml's compilation command takes in a `-pp` flag (preprocessor), which accepts a command that takes in a file and outputs an OCaml AST tree. We're basically using that. In that sense, the official OCaml syntax is really just that: another syntax like Reason, but official, and goes back two decades.
Because of the clean mapping from one syntax to another, you can toggle between the two fairly easily: https://github.com/facebook/reason/wiki/Newcomer-Tips-&-Tric...
In Announcing BuckleScript 1.0reasonml
reason
OCaml2016–2024
reasonml / reason
reason
Simple, fast & type safe code that leverages the JavaScript & OCaml ecosystems
27Distinct people
35Mentions
0Explicit recommenders
10.3KGitHub stars
What to know before exploring
What it is
Simple, fast & type safe code that leverages the JavaScript & OCaml ecosystems
GitHub
Where it is used
No documented product use was verified in the last source check.
What people are saying
No recommendation phrase was found in the indexed comments.
No classified warning is attached to this page. Read the discussions before treating silence as approval.
Also in these discussions
- meta/flow · linked in 3 of the same discussions
Mentioned in the same Hacker News threads. That is not proof they are substitutes.
This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 8:59:20 PM UTC.
No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.
Mentions over time
HN mentions by year35 dated mentions
Observed mentions: 2016-05-17 21:17:04 UTC to 2024-11-25 14:59:17 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2016 | 2016-01-01 00:00:00 UTC | 2017-01-01 00:00:00 UTC | 6 | 1 | 5 |
| 2017 | 2017-01-01 00:00:00 UTC | 2018-01-01 00:00:00 UTC | 11 | 2 | 9 |
| 2018 | 2018-01-01 00:00:00 UTC | 2019-01-01 00:00:00 UTC | 5 | 1 | 4 |
| 2019 | 2019-01-01 00:00:00 UTC | 2020-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2020 | 2020-01-01 00:00:00 UTC | 2021-01-01 00:00:00 UTC | 8 | 0 | 8 |
| 2021 | 2021-01-01 00:00:00 UTC | 2022-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2022 | 2022-01-01 00:00:00 UTC | 2023-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2023 | 2023-01-01 00:00:00 UTC | 2024-01-01 00:00:00 UTC | 3 | 0 | 3 |
| 2024 | 2024-01-01 00:00:00 UTC | 2025-01-01 00:00:00 UTC | 1 | 0 | 1 |
From the project README
An excerpt from the repository, fetched Nov 13, 2026.
Read the project’s introduction
Reason
Simple, fast & type safe code that leverages the JavaScript & OCaml ecosystems.
Latest Releases:
User Documentation
The Reason user docs live online at https://reasonml.github.io.
The repo for those Reason docs lives at github.com/reasonml/reasonml.github.io
Docs links for new users:
Getting Started
Community
Contributing:
npm install -g esy@next
git clone https://github.com/reasonml/reason.git
cd reason
esy
esy test # Run the tests
Contributor Documentation:
The docs/ directory in this repo contains documentation for
contributors to Reason itself (this repo).
License
See Reason license in LICENSE.txt.
Works that are forked from other projects are under their original licenses.
Credit
The general structure of refmt repo was copied from whitequark's m17n project, including parts of the README that instruct how to use this with the OPAM toolchain. Thank you OCaml!
Read the full README on GitHubWhat Hacker News says
6 sourcesSander sent a [Pull Request](https://github.com/facebook/reason/pull/647) to [Reason](http://facebook.github.io/reason/) which adds JSX syntax (which many React developers have found helpful)
Reason doesn't yet work with Edgar(OP)'s React bindings yet, but it could easily (and therefore JSX would work as well).
In Compile OCaml to JavaScript, use ReactJS, bindings to ReactJS, several examplesA Docker file for Reason development
56 points · Open discussionIt would be nice if they'll make it work on Windows platforms. There is already an issue for that[1]. It also depends from the Windows support in OCaml itself and opam[2].
[1] https://github.com/facebook/reason/issues/470
[2] https://github.com/ocaml/opam/issues/2191
In Reason: A new interface to OCamlI've worked on the Atom plugin for this, itself written in Reason and compiled to JS using js_of_ocaml: https://github.com/facebook/reason/tree/7f3b09a75cacf828dd6b....
Having worked with Reason, JavaScript, and the bridge between the two, most of my errors seem to fall on the JavaScript side. So I guess the type system's indeed working =).
In Reason: A new interface to OCamlThis looks very interesting. I've always had OCaml in mind but never actually got around to using it in a project. Facebook could have done a better job describing what exactly this is, but they do provide a good overview at the end of the page (strangely!) [1].
In summary, Reason [2] is a new language (correction: interface to OCaml) that shares a part of the OCaml compiler toolchain and runtime. I don't know of any language that uses a similar approach, that is, plugging into an existing compiler toolchain. I guess a reasonable yet inaccurate analogy would be Reason -> OCaml is like Elixir -> Erlang or Clojure -> Java.
I hope Reason can provide OCaml with the extra push needed to bring it into the mainstream PL space and more widespread adoption.
[1]: http://facebook.github.io/reason/#how-reason-works
[2]: https://github.com/facebook/re