Python and Ruby got adoption because they provided frameworks that made writing websites easy - Django and Rails respectively.

Node became popular because now front-end devs could write their own backends.

Go became popular because of Google and it's concurrency primitives (as far as I know)

Swift is going to become popular because of Apple and... fill in the blank.

My take is that it'll take good performance, and easy to understand concurrency primitives that make writing libraries and using them a joy - that's the only way.

That'll be the differentiating factor that'll entice people to pay attention - otherwise as you have pointed out, there are plenty of alternatives.

>Python and Ruby got adoption because they provided frameworks that made writing websites easy - Django and Rails respectively. Node became popular because now front-end devs could write their own backends.

So you are saying concurrency primitives aren't required for a successful server language?

Swift is at least an order of magnitude faster than python. It provides static typing. It compiles to native binaries. It's still fun to program in. There are already frameworks that allow programming web servers in Swift. It's more expressive than Go.

It's a matter of time for it to get traction.

The only thing python/ruby have going for them at the moment is momentum.

Remember in 2005, Python was a fringe language on the web. Most web programming was done in php.

There was a post about energy use recently. C, C++, Rust and Swift were often sharing the top 4 slots for various efficiency metrics. I would guess that energy efficiency is also a good metric for execution speed as well. Concurrency support is planned for swift, maybe efficiency, friendly syntax and concurrency support will be a winning combo?