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Add to SafariWhen comparing Java (via GWT) 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 Java (via GWT) is ranked 21st.
Specs
Question Ranking
Pros
Pro Strongly typed, good tooling
That's Java, so it is strongly typed, and we can use fully the IDE: error detection, refactoring, auto-completion, etc.
Pro Familiar for Java developers
Perfect if you have a strong background in Java programming, and need to code for the client side.
Pro Fantastic IDEs
Because Java is statically typed, integrated development environments (IDEs) for Java can provide a lot more feedback on errors you will encounter. Java IDEs can give you specific errors in the location where they occur without having to run the code every time. This makes is faster to debug and learn from your mistakes.
IDEs also have extensive auto complete capabilities that can help you learn the programming libraries you are using faster and tell you what functions are available.
Pro Most commonly used language in industry
Java is one of the most popular languages in industry, consistently ranking either first, or occasionally second (behind C or Javascript) in terms of usage. Polls (see sources below) show it to be consistently in high demand, particularly as measured by job board postings. This makes Java a great time investment, as you will be easily able to get a job utilizing your skills, particularly as those Java applications in production now will continue to need maintenance in the future. It also results in great support for tools and plenty of computer science books, example projects and online tutorials.
Pro Consistent programming standards
Most Java code follows very standardized coding styles. This means that when you're starting out, there are fewer questions about how you should implement something as the programming styles and patterns are well established and consistent. This consistent style means that it's often easier to follow others' example code, and that it's more likely to meet at least a certain minimum standard of quality. This discipline with consistent stylistic standards also becomes useful later, when collaborating on projects with larger teams.
Pro Highly optimized JavaScript
Produced JS is highly optimized, can be separated in modules with lazy loading, can be internationalized while loading only the chosen language.
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 Too verbose
- A Hello world needs package, class, static method and the actual
printf. - Reading a line from input requires instatiating 5 objects in the right order.
- Exceptions are everywhere, particularly since all values are nullable.
- Java has a getter/setter culture, but without native syntax support.
- portable Java code lacks anonymous functions, and continues to lack good support for partial application, compensating instead with verbose design patterns, kludges like anonymous inner classes, or just inline code.
- It is statically typed without type inference, with a culture that promotes long class names.
- Poor support for sum-types and pattern matching leads to overuse of inheritance for dynamic dispatch and chains of nested conditionals
Especially for beginners, this can make reading Java code feel overwhelming; most Java courses tell students to simply copy, paste, and ignore a significant percentage of the code until they've learned enough to understand what it means.
For experienced programmers, this makes Java feel tedious, especially without an IDE, and actively discourages some solutions and some forms of abstraction.
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.
