Yes, I understand that "code is data". This does not mean that data, in general, is code; unless you are willing to make the words completely meaningless. "Code" requires some notion of an execution platform/environment, which does not exist for arbitrary data. Here is a string: "the quick brown fox jumps over the lazy dog". Or how about "\u0000\u0000". That is not code, as generally understood.
> "Code" requires some notion of an execution platform/environment, which does not exist for arbitrary data.
Arbitrary data don't exist without some notion of an execution (or interpretation) platform.
We tend to use "code" as a word for "commands telling some execution process what to do" and "data" as a word for "information that is meant to be transformed" but in reality this distinction is meaningless; both are fundamentally the same thing, and even our "code" vs. "data" words have blurry borders. It's very apparent when you start reading configuration files. For example, aren't Ant "configuration files" essentially programs[0]?
We all know what we usually mean in context by saying what is "code" vs. what is "data", but one has to remember, that in fact they are the same - minding it leads to insights like metaprogramming. Forgetting about it leads to dumb languages and nasty problems, and is generally not wise.
Also I recommend watching http://www.youtube.com/watch?v=3kEfedtQVOY to learn how what would be data, as defined by formal grammars of some real-world protocols, can - by means of sloppy grammars and bad parser implementation - cross the threshold of Turing-completeness and become code.
I understand all this. Like many people, I've written programs in C++ templates. But I think we're talking past each other because you want to make a pedantic point. I'm using the words as they are generally understood, not in a technical computer science way. I'm talking about first-level stuff, not metaprogramming. Let me give you some questions to ponder:
- Is the text of Hamlet code?
- Was it code as soon as Shakespeare wrote it?
- If not, did it become code once the electronic computer was invented? Or did that happen once a version was stored in a way accessible to an electronic computer?
- Did all the existing paper copies immediately become code at that point as well?
> But I think we're talking past each other because you want to make a pedantic point.
I guess that's true.
The flavour of "code vs. data" discussion in this thread was one of representation formats. You could argue that when looking at works of art from past centuries one should immediately say "data!" [0]. But in case of JSON, a format suspiciously almost identical to Lisp in structure, one needs to be careful in saying "it's for data, not for code".
Actually, I'm not sure what kind of point I'm trying to make, as the more I think of it, the more examples of things that are borderline code/data come to my mind. Cooking recipes is the obvious candidate, but think about e.g. music notation - it clearly feels more like "code" than "data".
I feel that you could define a kind of difference between "code" and "data" other than in intent, something that could put bitmaps into the "data" category, and a typical function into "code" category, but I can't really articulate it. Maybe there's some mathematical way to describe it, but it's definitely a blurry criterion. But when we're discussing technology, I think it's harmful to pretend that there's a real difference. Between configuration files looking like half-baked Lisp listings and "declarative style" C++ that looks like datasets with superfluous curly braces, I think it's wrong to even try to draw a line.
[0] - there's a caveat though. "How to Read a Book" by Mortimer Adler[1] discussess briefly how the task of a poet is to carefully chose words that evoke particular emotional reactions in readers. It very much sounds like scripting the emotional side of the human brain.
