What is Source Code?

Bryan

Hey, I've got a question for you. Can you define source code?

Kyle

Seriously? Source code is source code. What's wrong with you?

Bryan

No, seriously! I'm having a philosophical debate with myself about what source code is and so far I'm losing. I need an outside opinion.

Kyle

Let's see. Hmmmm. Well, I'd say that source code is some human readable form that tells a computer what to do.

Bryan

What do you mean by 'human readable?' Do you mean that it's made of letters and numbers and other things that humans write with?

Kyle

Yeah, human readable, like with words and numbers and stuff.

Bryan

Does it have to make sense to people in order for it to be human readable?'

Kyle

Well, I guess so. To a certain degree anyway. I mean you wouldn't expect just anybody to be able to read it and make sense of it.

Bryan

Ok, so source code is something that's human readable, in the sense that some people may be able to make sense of it, that tells a computer what to do.

Kyle

Yeah, how does that sound?

Bryan

Full of holes!

Kyle

Such as?

Bryan

Well, your definition seems to imply that the human readable form is run directly by a computer. So basically everything that most people think of as 'source code' falls outside of your definition.

Kyle

Like what?

Bryan

How about source code that's run through an interpreter, or a compiler, or a VM!?

Kyle

You know what I mean!

Bryan

Suppose I don't! That's the point of the debate!

Kyle

Alright. Source code is something that's human readable, in the sense that some people may be able to make sense of it, that is processed in some way to produce some output that then tells a computer what to do.

Bryan

That's better. But let's say hypothetically there is a computer that can understand and follow the instructions in the human readable form?

Kyle

I think you're splitting hairs here.

Bryan

Humor me.

Kyle

Fine. Source code is something that's human readable, in the sense that some people may be able to make sense of it, that may be processed in some way to produce some output that then tells a computer what to do, or is interpreted directly by the computer. Satisfied?

Bryan

Not even close. What's this computer you speak of?

Kyle

You're kidding me, right?

Bryan

Nope.

Kyle

A computer, ya know? A thing that runs the source code or the stuff output by the process that processes it.

Bryan

Interesting take on things. Ya know, I seem to recall the word 'computer' has many meanings. Before there were computing machines there were people whose job was to run computations. They were called computers. So far both the machine and the human definition of 'computer' fit your definition of 'source code'.

Kyle

Oh god, what's wrong with you?

Bryan

Pedantry. But I wouldn't say it's something that's wrong with me. Can you define computer for me?

Kyle

...

Kyle

A computer is an electronic device that performs computations.

Bryan

Humans use electrical impulses...

Kyle

ARGH! Fine, an electronic device that you plug in that performs computations.

Bryan

Well, that definition seems rather crude, but I'll accept it just to keep the ball rolling. So what about configuration files? They're human readable and tell a computer what to do. Take emacs for example, its configuration is a bunch of data structures that get interpreted by emacs, well the lisp interpreter part of emacs anyway and are run.

Kyle

What's with you and that stupid editor?

Bryan

What's with you and your stupid editor? What's it called again? 'six?'

Kyle

It's called 'vim' and if you're truely going to be pedantic, VIM in roman numerals is 6000.

Bryan

Whatever, both the fact and question remain.

Kyle

What fact?

Bryan

Your editor sucks.

Kyle

It does not suck, it's awesome. You just don't grok it.

Bryan

Look, why are you arguing with me about text editors? We're supposed to be talking about source code.

Kyle

Very well. I'm not sure that I agree with your assertion that configuration counts as source code. It doesn't tell the computer what to do, it tells a program what to do.

Bryan

That's true, it does tell the program what to do not the computer. But the configuration is still human readable, and processed, and tells the computer what to do. Maybe there's no intermediate form that's produced but I don't see that as being the sole determinant between source code and configuration. If that were the case then source code for an interpreted language would be considered configuration if the interpreter simply walked over the AST.

Kyle

Yeah but, it's configuration. I think you picked a bad example since most people think of lisp as a language, not configuration. What about simple configuration files that are just key-value pairs.

Bryan

I would argue that it could still be considered source code depending, of course, on what's reading and interpreting the configuration. I would say Turing-completeness shouldn't enter the picture at all. Simple configuration or extremely rich configuration doesn't matter. Some people consider HTML and CSS to be source code, but neither are Turing-complete. Conversely what about TeX and PostScript? Both are Turing-complete but nobody considers documents in either to be source code.

Kyle

Look, I'd love to debate with you about what is and isn't source code but I have some work to do that involves writing source code, not just thinking about it.