When comparing ElixirScript vs Swift, the Slant community recommends ElixirScript for most people. In the question“What are the best languages that compile to JavaScript? ” ElixirScript is ranked 26th while Swift is ranked 46th. The most important reason people chose ElixirScript is:
Uncluttered, yet unambiguous syntax
Specs
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Pros

Pro Clear syntax
Uncluttered, yet unambiguous syntax
Pro Great for concurrency
Leverages the existing Erlang BEAM VM

Pro Excellent community
The Elixir community has proved to be welcoming and very supportive.
Pro More familiar syntax
All of the benefits of Erlang; without as steep a learning curve of prolog based syntax. Elixir is heavily inspired by Ruby's syntax which many people love.
Pro Great documentation
Elixir's documentation is very good. It covers everything and always helps solving any problem you may have. It's also always available from the terminal.
Pro Modern syntax
Pro Swift is closer to other platforms
Apple’s modern programming language is easier to understand for non-iOS developers and minimizes time for additional explanations and clarifications. Moreover, Swift can be used as a script language. It is an interesting solution for the iOS community to unify writing of build scripts. At the time being iOS developers are split up in regard to this activity. Some of them write build scripts in Bash, others use Ruby, Python, etc. Swift gives an amazing opportunity to be applied to all iOS programming needs.
More details can be found here https://mlsdev.com/blog/51-7-advantages-of-using-swift-over-objective-c
Pro Works with Apple's Cocoa and Cocoa Touch frameworks
Pro Can be used as a Just-In-Time language
Pro Inherent parallelism
Pro Low memory footprint due to reference counting
Pro Backed by Apple
Pro Performance speed comparable to native C
Pro Swift has some clever tricks up its sleeve
Due to having elements of a functional programming language. Things like 'map' and 'filter' for example.
Pro Uses LLVM compiler and Obj-C runtime allowing C, Objective-C, Objective-C++ and Swift code to run side by side within a single program
Cons
Con Swift is a moving target
They've released 1.2 so far, and 2.0 is coming soon. Every small update brings adjustments to paradigms (such as how to do type casting) that can be a little frustrating to absorb. Objective C was also constantly updating, however, but not at the same rate these days.
