Sure, but in a lot of today's apps there are no performance critical parts. They're already well under the ceiling of what the hardware can do all the time or t

Sure, but in a lot of today's apps there are no performance critical parts. They're already well under the ceiling of what the hardware can do all the time or they spent 95% of their CPU in optimized routines in the OS/kernel. Of course, a more expressive but faster language like Mirah or Kotlin or Go something would be ideal here. The problem with writing glue code in a scripting language is that it doesn't really buy you much unless you can impose a new, higher-level abstraction on the existing UI. As these examples show, you haven't really improved on Cocoa if all you've done is changed the function calling syntax.