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Add to SafariWhen comparing Earl Grey vs Reason ML, the Slant community recommends Reason ML for most people. In the question“What are the best languages that compile to JavaScript? ” Reason ML is ranked 10th while Earl Grey is ranked 29th.
Specs
Question Ranking
Pros
Pro Powerful hygienic macros
Earl Grey's macro system allows for creating powerful control structures that look just like builtin ones. EG also supports macro libraries which allows developers to provide their macros/DSLs for others to use.
Pro Pattern matching
Pattern matching is an incredibly powerful tool that, once you've tried, you cannot live without. This is not your average hacked-together pattern matching but a complete and integral feature to the language.
Pro ECMAScript 6 Asynchrony
Earl Grey provides Promises based on ECMAScript version 6 and as many NPM libraries already implement. Earl Grey also provides a promisify function that converts old-fashioned callback-style asynchrony to promises.
Pro Fully compatible with Node.js ecosystem
Anything available on NPM can be used just as easily with Earl Grey. In fact, everything else can be used too! Earl Grey has interfaces to Browserify, Webpack, and even experimental support for SystemJS. Earl Grey can even be used to generate npm packages that any node-compatible language can use!
Pro Uses the excellent Bucklescript Ocaml to Javascript transpiler
Pro Superior type inference
Ocaml type inference is so smart that you never have to repeat yourself and keep code very clean, type errors also are very pleasant.
Pro Aims to make the transition from Javascript easier
Despite being a completely different language Javascript programmer will find that the syntax of ReasonML has many familiarities with Javascript.
Pro Uses established compiler technology from Ocaml with a tweaked syntax that leans more towards Javascript
Pro Removes JavaScript "bad parts" but sticks to it's design philosophy
unlike other js-targetting languages that are thought as a way to have a language that pleases community X run in a browser, reason is really designed with JavaScript community in mind. it removes the bad parts but keeps its syntax and its best design principles (from Scheme): simplicity, minimalism, and functions as building block.
Pro Immutability with escape hatches
reason includes true immutability, but it has escape hatches to let you use mutations in exceptional cases.
Pro Compiles to JavaScript or assembly (ocaml)
The same reasonml code can compile to js (eg. run on browsers or node.js, use any lib in npm), or compile to assembly thru ocaml (unless of course you load js externals), running on any device, with C-comparable (or better) performance.
Pro JSX syntax natively supported
Reason was created by the creator of react, for developers already using JSX to template web or native UIs this results very familiar.
Cons
Con Not true static typing
EG gives you the tools to implement your own type-checking inside of argument lists and elsewhere but there's no analysis done at compile-time like other compile-to-js languages.
Con Unfamiliar syntax
While the language shares a lot of DNA with Python, there are still many new (and interesting) features/sugar that may take some time to get used to.
Con A standard async syntax is pending
Async syntax is not standard across native/js projects and in both cases a bit awkward for non-ocaml devs. Currently this is reasonml most voted issue in their GitHub repo so hopefully, there's news soon.
Con Ecosystem is a mess
A wonderful language, but a user is required to use multiple different package managers for many things (esy, bsb, npm). Some standard templates from bsb (e.g. react-starter) are not installable out of the box.
