Comment by cayley_graph

I mentioned speed because they're writing their own instead of using Chez or Gambit or something (which have taken a while to get into 'performant' territory). Writing and maintaining a fast(!) Scheme is hard. Having spent time with r5/r6/r7rs (many variants for the latter) and their quirks I'd honestly say Lua is simpler by a wide margin, but some of this is down to preference. The Lua execution model, if nothing else, is a lot easier to understand than call/cc for instance. And the language does force you to write things functionally, practically speaking. I'm also not a huge fan of syntactic macros. Also things like dynamic binding which, in fairness, are just SRFIs but end up being implemented by most Schemes. I do respect their willingness to do what's fun for them, though :) that's what it's all about.