Look into F#.<p>It&#x27;s open source. Works on Linux, Mac OS X, Android, iOS, Windows, etc. It has a good ecosystem and tooling built around it already but you can also tap into the C# ecosystem, if necessary.<p>It compares really well to Swift: <a href="http:&#x2F;&#x2F;www.slideshare.net&#x2F;ScottWlaschin&#x2F;swift-vslanguagex" rel="nofollow">http:&#x2F;&#x2F;www.slideshare.net&#x2F;ScottWlaschin&#x2F;swift-vslanguagex</a> but even without that comparison, it&#x27;s worth a look on its own.