My instinct has always been that it should not. Sadly, there are always foolish souls who will not accept my instinct as definitive evidence, and so one must stoop to logical arguments instead.
Significant whitespace, by definition, places the burden of formatting on the programmer. In return, it can be leveraged to reduce syntactic noise such as semicolons and matching braces. The alleged
benefit is that in practice, programmers often deal with both formatting and syntactic noise, so eliminating one of the two is a win.
However, this only holds in a world without civilized tooling, which in turn may explain the fondness for significant whitespace, as civilized tooling (and anything civilized, really), is scarce. Once you assume proper tooling support, a live pretty printer can deal with formatting as you type, so there is no reason for you to be troubled by formatting. So now you have a choice between two inconveniences. Either:
- You use classical syntax, and programmers learn where to put the semicolons and braces, and stop worrying about formatting, Or
- You make whitespace significant, cleanup the syntax, and have programmers take care of the formatting.
At this point, you might say this a matter of personal preference, and can devolve into the kind of religious argument we all know and love. To tip the scales, pray consider the line of reasoning below. I don’t recall encountering it before which is what motivated this post.
In the absence of significant whitespace, a pretty printing (aka code formatting) is an orthogonal concern. We can choose whatever pretty printing style we like and implement a tool to enforce it. Such a pretty-printer/code-formatter can be freely composed with any code source we have - a programmer typing into an editor, an old repository, and most importantly, other tools that spit out code - whether they transpile into our language or generate code in some other way.
Once whitespace is significant, all those code sources have to be cognizant of formatting. The tool writer has to be worried about both syntax and formatting, whereas before only syntax was a concern.
You might argue that the whitespace is just another form of syntax; the problem is that it is not always context-free syntax. For example, using indentation to nest constructs is context sensitive, as the number of spaces/tabs (or backspaces/backtabs) depends on context.
In short, significant whitespace (or at least significant indentation) is a tax on tooling. Taxing tooling not only wastes the time and energy of tool builders - it discourages tooling altogether. And so, rather than foist significant whitespace on a language, think in terms of a broader system which includes tools. Provide a pretty printer with your language (like in Go). Ideally, there's a version of the pretty printer that live edits your code as you type.
As a bonus, all the endless discussions about formatting Go away, as the designers of Go have noted. Sometimes the best way to address a problem is to define it away.
There. That was mercifully brief, right? Nothing to it.