Comment by userbinator | Hacker News Reader

Comment by userbinator | Hacker News Reader

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but they are not obvious to an external viewer

That's precisely the point. The whole philosophy of APL is that it's not supposed to be obvious to anyone who doesn't (yet) know it. However, seeing as the character set is still Latin, it's not hard to guess at what it does even if you don't know the language.

- I don't see 'vs' in the snippet, but would guess V stands for Vector.

- Even in all but the most anal "standard style guides", single-character names are normal for temporary/limited-scope variable names.

- You could likewise ask why Chinese words aren't separated by spaces, or why English words need to be. It's a different language with its own grammar and style.

I don't know APL either, but at least I make an effort to see their perspective on the language, because it is clear that there are people who are highly proficient at working with code like this. (Likewise, I would guess that experienced APL'ers probably find more "traditional" languages like C, Java, Python, etc. "unreadably" verbose.)

V for Vector is an appropriate, but not the only, interpretation for that letter.

In the case of this compiler, I take an opposite convention. Most single character names are globally meaningful, and their meaning rarely, if ever changes across the whole compiler. As names get longer, they progressively represent more local elements. This is done in a way that reveals that nesting structure, but is also done because over time I realized that it was harder to remember from one patch to the next what the local variables were meant to do, rather than the global variables, which were almost always the same all the time and were much more likely to be in mental cache. Therefore, I used more "information", that is, more characters, for local names that I would more likely forget the meaning of later, than for global names that were universal and almost always on my mind.

And yes, I did try doing this compiler in many, many other styles, including C, C++, Nanopass Scheme, ML, Java, Cleanroom, traditional APL style, and so on and so forth. They were all unreadably verbose and difficult to work with and very hard to make forward progress on.

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