Reason ML vs C#

Ocaml type inference is so smart that you never have to repeat yourself and keep code very clean, type errors also are very pleasant.

Despite being a completely different language Javascript programmer will find that the syntax of ReasonML has many familiarities with Javascript.

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.

reason includes true immutability, but it has escape hatches to let you use mutations in exceptional cases.

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.

Reason was created by the creator of react, for developers already using JSX to template web or native UIs this results very familiar.

.NET offers rich functionality.

The Visual Studio IDE offers one of the best development environments. The Community Edition and Visual Studio Code can be used for free.

Can be designed visually with the Visual Studio designer for traditional Windows forms, WPF, or Web forms.

Lot's of tools and libraries available.

With Xamarin for Mobile (ios, android),
with .net core asp for server (linux, windows),
with .net core for desktop (windows, mac),
with mono for desktop (windows, linux),
with blazor for web client with webassembly.

However, it is not considered top for any of those categories, but it is top choice for Windows desktop with .net framework and top choice for Unity.

.net 5 will unify frameworks similar to JVM (just one).

Runs on Linux, Mac, and Windows.

Constant updates and bug fixes to many popular frameworks, as well as great first-party support from Microsoft. This can be a con as well in certain circumstances.

Being a C like language counts in favor for it as a general purpose programming language, given the ease of using existing skills to pick up this language easily.

There are other superior languages that could be used as a general purpose, such as: F#, Haskell, but the complexity of those languages, being functional, make them strange to the usual C Syntax.

C# is better than C whenever garbage collection, Objects, classes, data access, are needed. But C is going to be the choice when hardware access and performance are paramount.