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Comment by _bxg1 | Hacker News Reader

What's the editor support like? TypeScript has industry-leading editor integration with insanely fast response times. I'm always wary of new languages for this reason; I've been burned before by Facebook's own Flow type system.

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As far as editor support, I have used reason-language-server (https://github.com/jaredly/reason-language-server) with Emacs (current), Vim and VSCode (provided through reason-vscode plugin).

I used to use IntelliJ, and there was a solid plugin for that as well.

ReasonML's compiler is way faster than Typescript's.

There's a difference between "the compiler is faster when run at the CLI" and "the language server is faster". A good language server remains responsive by doing quick, partial compilations on just the section that changed. A bad language server just wraps the standard compiler and re-runs the whole thing when a file is saved. The latter will eat up CPU/RAM and make for a frustrating dev experience, no matter how relatively-fast the base compilation time is.

OCaml (the Reason compiler) has historically had excellent (and fast) editor support tooling: Merlin.[1] That is now being packaged up as a language server (i.e., LSP).[2] Once you try a Merlin-based editor addon, everything else will seem dog-slow.

[1] https://github.com/ocaml/merlin

[2] https://github.com/ocamllabs/vscode-ocaml-platform

True, I've been spoiled by merlin ;)

1. The language server, reason-language-server is written in native Reason and is _very_ fast.

In terms of compiler speeds, Draftbit has 1,000 ReasonML components and about 100 TypeScript files.

I can safely build AND type the entire ReasonML project before TypeScript returns the type results in watch mode.

I'll take super fast compilation first ;)

The standard compiler can do a cold compile of a single file in milliseconds. When the compiler is that fast you _can_ just wrap it up and it'll still be faster than TypeScript.

But to answer your actual question: The current standard (reason-language-server) does simply wrap the compiler, and it's more than fast enough, but the community is working on a new merlin-based language server (ocaml-lsp) which does support partial compilation.

Reason support in VSCode is very solid.

That's not even true. It's still very early days for Reason VSCode tooling, since you might find a few extensions that support most of the cases but lacks a few key features that you might be used to while writing JS/TS.

I use the Reason Language Server and eglot in emacs on a linux system and it is very snappy. Reason-cli gives you code formatting also.

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