When comparing Reason ML vs V, the Slant community recommends V for most people. In the question“What are the best functional programming languages for programming beginners?” V is ranked 6th while Reason ML is ranked 13th. The most important reason people chose V is:
V is easier than C and fast like C.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
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.
Pro Fast like C
V is easier than C and fast like C.
Pro C Interop
Can import C libraries, structs, and headers.
Pro Cross-platform
Compile to many OSes.
Pro Simplicity
V is simple and powerful.
Pro Can create multi-OS GUIs
Multi-OS GUI creation is more integrated into the language than others.
Pro Clear syntax
Highly understandable language.
Pro Sum types
V has Sum Types.
Pro Generics
V has generics.
Pro Closures
V has closures, which gives the user additional options and usefulness.
Pro Safety
V is very safe.
Pro Single paradigm
Follows the philosophy that there should be only one way to do something, as opposed to multi-paradigm languages like C++.
Pro Supports concurrency and channels
Can run functions concurrently that communicate over channels.
Pro Fast compile times
Compiles programs fast, less waiting around, so more productive and fun.
Pro Friendly and helpful community
Just check the V Discord channel or their GitHub Discussions and you will see by yourself.
Pro Inline assembly
Can add Assembly code.
Cons
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.
Con Rapid changes in a language syntax/features
Since V language under a continuous development and core syntax and features will be "frozen" in a version 1.0.0, updating from older version of a language can cause a code rewrite of previously working program.
Con V 1.0 release was planned for December 2019
The first version of the language was publicly released in June of 2019, version 0.1.x. First beta version of the language was released June of 2022, version 0.3. x. Language has progressed faster than most. Welcomes contributors to join the project.