Not sure if you're still reading this thread or not, but I thought I would try to clear up some of the questions you have here for you.
> so now im running anarki in dr scheme right?
Well, not exactly. MzScheme is the name of the Scheme programming language implementation that you are running anarki in, DrScheme is basically a nice GUI front end to the MzScheme language.
> what was this GIT stuff i downloaded? i thought it was some sort of IDE?
No, Git is not an IDE. It is software that is used to manage source code. In other words, using Git, you get a history of changes made to your source code allowing you to rollback changes and create new branches where you can develop new features without fear of breaking the currently working build of your software. The reason you downloaded it is because it is the source control software that the Anarki developers are using to manage the Anarki source code, so you need it to get a copy (i.e., a clone) of the current working version of Anarki.
> what do you use to edit/compile? is there something better than DrSceheme?
Everyone uses MzScheme to compile and execute Arc code, because that is the language that Arc was written in. There are other implementations of Arc on the JVM (aka Java Virtual Machine) and another that compiles to C, and I believe one in Common Lisp, but none of these are official implementations of Arc (i.e., created by Paul Graham). As for editing Arc code, well you can use whatever you want to edit it. Personally I'm an Emacs fan, so I use it for all of my editing, but I'm sure Vim, TextMate, etc., etc. would do just as well. If you are looking for an editor in which you can also execute your code, then Emacs or DrScheme should work.
I hope that clears up a few of your questions for you, good luck in your studies.
Not sure for the case where (< pow 0), though. Just run the tests, but I think the tail-recursive function is at least as fast as the iterative one. Actually, in fine, iterative code is transformed into its tail-recursive equivalent : code involving for is transformed as a bunch of tail-recursive functions for example.
how can it be so much faster? its written in C or something? its built in the language somehow i guess, its not possible to recreate for me by writing a def?
It is probably written in C and does not check its args every time it is called. Basically, every time you call 'is, '<, '+, or any other primitive operation, it checks whether its arguments are numbers, then performs the operation. All these checks are useless since, within the body of your function, you know the type of your args are numbers, but you cannot avoid them anyway. Optimization will come, later :)
ah solved it now by reversing the variables.
but lets say you have a function where you dont know before hand, how would you solve that?
edit: changed variablename too.
take a look at http://arcfn.com/doc/iteration.html for a list of different iteration functions. since you aren't using the x variable in those for loops there, you could just use repeat:
They aren't ignored, they just don't do anything. for can take any number of arguments: the first is the symbol, the second the start value, the third the end value, and the rest are all the body of the loop. They all get executed in every iteration. For example:
In this case it's not causing a problem. You're allowed to give parameters whatever name you want, but if you name the parameter after the function then you can't call the function from within itself because the name will now refer to the argument.
So if you don't need to call the function recursively, there's no harm. It's just a bit confusing.
