This is so exciting to see! I became obsessed with Inform7 a while back after I learned about it from "The best things and stuff of 2014" [1]. I remember scouring the web for its source code and being really bummed it wasn't open source. I can't wait to finally dive in! I've never seen a literate program of this scale before.
I think Apple is primarily trying to attract artists and other creative types with the Pro. A good friend of mine is planning on giving up his Wacom and moving to an iPad Pro instead.
I used Ada during my first internship (avionics software). However, the group I was part of was in the middle of phasing out Ada in favor of C/C++. This was around 2010-2012.
I feel the need to point out that you can run Mac OS X on pretty much any recent Intel processor and a wide range of motherboards. It is not locked to Apple hardware.
[1] http://blog.fogus.me/2014/12/29/the-best-things-and-stuff-of...