TeX is very Turing complete. As is Java sans semicolons, C macros, and many other things that probably shouldn't be. Right now, I'm trying to figure out what the minimum number of characters you need in Ruby is to make it Turing complete. I'm pretty sure that if you restrict yourself to under 12 characters, it's still possible.
As in the minimum character set? As of 1.9.2, you can do lambdas with a = ->(x){do stuff} and call them with a[3]. So I think you could probably translate to SKI calculus using only: (){}->[]
Since SKI gives you lambda calculus, and the lambda calculus is turing complete, you might win that way. :)
But what's in that string? That still counts. What I should have done was put an additional restriction on what IO is available. Otherwise, something like "eval `cat f`" or something could be all powerful.
Sure, but it counts regardless of what you're talking about. We don't generally talk about charging data against the TM because they all need data of some sort to do anything interesting. "eval" still gets you there. (Pedantic.)
I should have phrased as "what is the minimum number of characters that need to be seen by a Ruby parser in order to have something Turing equivalent to Ruby without a limited character set?"
