Lambda the Ultimate

I find the colour highlighting used Vim works for me, to the degree that when I am using a system that does not have it, I definitely miss it. Looking at the first example I find the boxes and background colour changes too much. The second example just looks a mess, in general too many fonts just make a document unreadable.

I find the use of bold acceptable, and maybe italic. I used to find the default black and white output of a2ps on C/C++ code acceptable.

So i find the sweet-spot is restrained use of colours and styles for keywords, literals, and meta-syntax (includes / comments etc).

My personal experience of syntax highlighting is that I appreciate when it makes obvious some parsing tasks that I would have to do myself otherwise:

- lexing string literals and comments (I find that having comments in a different font, eg. italic, helps making them easy to abstract away)
- recognizing keywords as opposed to identifiers (bold, or a different color, is fine for keywords)

I think the question should not be "what do we want to highlight?" but rather "how does it help to have this highlighted?". Your conclusions are otherwise essentially the same as mine.

I think keywords, where they are recognised as tokens, and are therefore not permitted to occur elsewhere in the syntax make sense to me. For example:

let let = let in let

Although it is possible to make some sense of this with backtracking parsers, usual way to avoid ambiguity is to treat 'let' as a reserved word that always introduces a let binding, and is never a variable name. In such cases the highlighting helps distinguish the special syntactic behaviour.

The same thoughts apply to comments, literals, and meta-syntax.

IE, for me colour coding makes sense in terms of the syntactic category a token belongs to, hence an expression would all be the same, no need to pick out functions, variables or operators.

It helps to have this highlighted because the syntactic-categorys behave differently, keywords take parsing preference over other interpretations, as do comments. Its very helpful to have all code between begin-block and end-blocks marked.

using small caps for something where case is actually relevant is an obviously bad idea

I think the idea was to create a new language with these properties. This isn't 'syntax highlighting'. This is 'typography as syntax'. JavaScript just provided an initial example.

Whether we consider this good/bad typography is a separate issue. I also found it pretty ugly. But I did like the small caps idea.

OK, fair point. That would make more sense.

I would not buy a car from Ling, though I heard he was very successful.

She was very successful. ;)

yes, i have day-dreamed of a way for the ide to gently color things that interact. so things that are related statically, and then eventually also even things that are run-time related. there's all sorts of things that could be investigated. and if we gather run time stuff we can do things like colorize based on performance or security or resources or whatever else. seems like there's more we could do than we have already done.

Harlequin Dylan which became Functional Developer and is now Open Dylan had syntax coloring in the editor for the optimisation the compiler was performing on method dispatch.

You could see whether methods had been inlined, statically determined or were virtual dispatched by the color. It was pretty nifty.

We had this in the Scala IDE, and to be honest...it was quite ugly. Not only ugly, but it wasn't very useful as a guide for the reader.

In truth, color is a scarce resource: if you overuse it, it becomes useless and annoying. Instead, dramatic color-change should be used sparingly as a highlight; slight color changes are alright (e.g. colors that are very close to each other to be recognizably different but easily ignored).

I've been very conservative about color usage in YinYang. And having most of the code be a shade of black is actually useful: highlight keywords and constants in a different color, but reserve most of the dramatic color budget for meta text.

"What we need is subtlety... and lots of it!"

Just because one might use colors (as in, different hues) doesn't mean they have to be a rainbow or anything un-subtle. There's an art in such things (maybe even a science or two). So don't throw the baby out with the bathwater, please.

And, for Pete's sake, if you trust a bunch of programmers (other than me, the exception to prove the rule) to pick the color scheme then duh it will have high probability of sucking. It is like expecting any kind of Linux desktop to ever not majorly suck, etc.

So you fix the use of color as part of your language design.