Oops, sorry, must have lost track of your post, Ruatha... I haven't done anything on a graphical shell yet, but what I am doing is completely rewriting the program to make it faster and more powerful. See, right now, it's horribly inefficient at parsing the text, because basically if you have 5 + (2 * 3), it searches for the outermost operation (the plus), and splits it up into two expressions, 5 and 2 * 3. Then it takes the 5 and says "oh, that's a number", and stores it away. The 2 * 3 then gets parsed AGAIN (even though it was already searched through to find the plus) and split into the 2 and 3. Then, those numbers are multiplied to get 6, and then 5 is added to get 11. This may not seem to inefficient, but imagine a long expression with many subexpressions, such as sin(pi * (2 + atan(6) * e) - 1?
So what I WANT to do is do all the parsing at once, only once, and THEN do the evaluation. This will involve something I've come up with called "functional notation" where every operation, constant, or variable is represented as a function, so for instance 5 + 2 would be represented as +(5,2), and sin(pi / 3) would be represented as sin(/(pi(),3)). Actually functional notation has probably been invented already, but I thought of it independently, so there
Which leads me into the main reason for this post: I noticed that using functional notation, there could only be one function or operator with the same name and "arity" (which is the number of operands). This reminds me a LOT of a programming language called Erlang, because there was the same restriction on Erlang's functions, seeing as Erlang was a weakly-typed language. SO... what I'm thinking of doing is, while I'm already rewriting everything, adding a *scripting language* to my expression evaluator, so that you can define your own functions without having to compile any C# code. Basically, I'd have only the most rudimentary functions and operators predefined, and the rest would be called through script. I know, you say scripting Languages are slow, but C# has this nifty feature which lets you compile and execute code "on the fly", so I could compile the scripts whenever the program is run (don't worry, C# code compiles fast
), and then execute them as compiled code in memory!
SO... what my question is, is what would be the preferred language of the Users of this program to base the scripting language on? The most natural choice for me would be C#, because that's what I use, but VB would work as well, since the on-the-fly compiler can work with either language. But since I'll probably have to write my own language parser (to allow only harmless instructions like "return x+y" and "if p then loop until q" and nothing like "delete c:\windows\*.*"
), I could just as well base it on some other language, like Python or Erlang... problem is, I don't know much ABOUT Python or Erlang...
So, anyone have a preference?