PureScript vs F#

Has Typeclasses and RankNTypes

The Eff monad, which is used for FFI code, optimizes out calls to bind, and supports tail call optimization, resulting in clean, efficient Javascript. The psc compiler also specifically recognizes the ST monad, and transforms scoped variables into mutable Javascript variables, for even more efficient code.

Compiling should be your first unit test. A tight type system (static and hopefully strong) will catch many logic errors that are often difficult to spot through debugging. In languages like PureScript, if it compiles, it often runs properly.

You cannot have side effects, unless a function is explicitly defined as so.

Modules compiled to CommonJS can be included with 'require', making it incredibly simple to call Purescript code from Javascript.

FFI system is quite good and easy to use. You can import functions curried or not curried. Records and arrays use native JS objects and arrays.

The Purescript website has fairly thorough documentation for all of the language's features, and the Purescript blog contains several examples of practical usage.

Thermite (React)
Halogen (VDOM, similar to ELM)
And hit these up with Signals, Isolated/(Managed?) Components, powerful functions and FFI

F#'s syntax tends to be terse while remaining very readable and easy to understand without being a chore to write.

Since F# is not a purely functional language, it lends itself to being more easily picked up by programmers that have experience with other paradigms.

Since F# runs on the Common Language Runtime or CLR, it has access to the entire .NET Framework, as well as libraries written in other .NET languages such as C#, VB.NET, and C++/CLI.

Forget Xamarin and Mono. F# now runs on the multiplatform .Net Core!

Thanks to a project like Fable, you can write and run your client app in F# and run it over JavaScript. It allows you to share code between your server and client.

This is a .Net language natively supported by Visual Studio. Though it is not as tooled up as C# the support is still substantial. In particular, C# deployment scenarios can be enabled for it with small C# wrapper projects. Integration with Visual Studio provides: IntelliSense, debugging, projects an other features.

F# directs you into a workflow where the right way is the path of least resistance.

Coming from a C# background, its restrictions might feel arbitrary at first (e.g., what do you mean my code has to be in dependency order!? Arbitrary alphabetical or bust!), but you'll soon realize that your code is cohesive, concise and consistent in a way that it never was before - and you can compile and run with confidence!

Thanks to Xamarin, F# is a functional language that you can use to build for iOS, Android and Windows.