When comparing Kotlin vs Fay, the Slant community recommends Fay for most people. In the question“What are the best solutions to "The JavaScript Problem"?” Fay is ranked 11th while Kotlin is ranked 25th. The most important reason people chose Fay is:
Fay produces smaller output than pure Haskell compilers such as GHCJS; It does not need to include the whole Haskell runtime, as it drops support for features such as multi-threading, giving it fewer dependencies.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Great tooling support
Since Kotlin is made by Jetbrains (the developers of IntelliJ IDEA) so it stands to reason that the IntelliJ support for Kotlin is also great. Besides that, Kotlin also works well with existing Java tools such as Eclipse, Maven, Gradle, Android Studio, etc...
Pro Easy adoption for existing Java programmers
Kotlin runs on the JVM and Java interoperability has been one of the main objectives since the language was born. It runs everywhere Java does; web servers, mobile devices (Android), and desktop applications. It also works with all the major tools in the Java ecosystem like Eclipse, IntelliJ, Maven, Ant, Gradle, Spring Boot, etc.
All of this makes adoption extremely easy even for existing Java projects. On top of this there's also ensured Type safety and less boilerplate code needed.
Pro Easy to learn if you have prior programming experience
Kotlin's syntax is extremely easy to understand. The language can be picked up in a few hours just by reading the language reference.
Pro No runtime overhead
The standard library is relatively small and tight. It mostly consists of focused extensions of the Java standard library and as such adds no additional runtime overhead to existing Java projects.
Pro Officially supported for Android development
Starting with version 3.0 of Android Studio, Kotlin support will be built-in. This means that it's now easier than ever to use Kotlin for existing Android projects or even start writing Android apps only with Kotlin from scratch.
This also means that Kotlin and Kotlin plugins for Android Studio will be fully supported in the future and their likelihood of being abandoned is quite small since Google is fully embracing the language for their Android ecosystem (alongside Java and C++).
Pro Low-risk adoption for existing Java codebases
Since it has such a good interoperability with Java, Java libraries, and Java tools. It can be adopted for an existing Java codebase at little to no cost. The codebase can be converted from Java to Kotlin little by little without ever disrupting the functionality of the application itself.
Pro Does not impose a particular philosophy of programming
It's not overly OOP like Java and it does not enforce strict functional paradigms either.
Pro Is built to solve industrial problems
Kotlin has been designed and built by developers who have an industrial background and not an academic one. As such, it tries to solve issues mostly found in industrial settings. For example, the Kotlin type system helps developers avoid null pointer exceptions. Reasearch languages usually do not have null
at all, but APIs and large codebases usually need null
.
Pro Small output
Fay produces smaller output than pure Haskell compilers such as GHCJS; It does not need to include the whole Haskell runtime, as it drops support for features such as multi-threading, giving it fewer dependencies.
Pro Simple, flexible, hackable FFI
As with UHC, the FFI to Javascript works with printf-style format:
max = ffi "Math.round(%1,%2)"
This can simplify code needed to make calls to methods on objects, in contrast to e.g., Purescript's FFI, which requires that methods be wrapped in Javascript. Similarly to UHC, Fay also supports the use of %*
, for javascript functions with arbitrary numbers of parameters, such as concat
, though they must expose an explicit number of parameters to Fay.
Pro Easy to set up, with packages available on Cabal
Fay is available on Cabal, as are Fay packages, so getting up and running is as simple as typing 'cabal install'. Happstack, Snap, and Yesod packages are available on Hackage, as are bindings for JQuery and Backbone.
Pro Subset of Haskell - nothing new to learn
Since Fay is a subset of Haskell - Lazy, statically typed, and pure by default. There's no new syntax to learn, and no surprises when it comes to the semantics of your code. This extends into function names as well - Fay programmers can use familiar functions such as putStrLn
to output to the console, rather than Javascript-specific versions.
Cons
Con May be hard for programmers already used to imperative style to learn functional programming from Kotlin
Since Kotlin does not enforce any particular paradigms and is not purely functional, it can be pretty easy to fall back to imperative programming habits if a programmer comes from an imperative background.
Con The need for Java interoperability has forced some limitations
The need to make Kotlin interoperable with Java has caused some unintuitive limitations to the language design.
Con No typeclasses
This can cause some overhead.