Comment by fc417fc802
13 hours ago
> In what scenario would you ever need to use a sequence like <tab><space><tab> in indentation in your source code?
Writing a lisp in an editor that doesn't do boneheaded things with tabs? That's the only one I've personally run into but lack of imagination is hardly a good excuse to implement arbitrary restrictions.
> Let alone using esoteric Unicode whitespace characters for indentation.
How do you know what's esoteric in other countries? I certainly don't. I'm not an expert in linguistics but I'm sure that people everywhere in the world write computer programs at this point.
> I think it is perfectly reasonable ...
Without any concrete justification? Why would entirely artificial restrictions ever be seen as reasonable?
What "boneheaded things with tabs" are you referring to? The picture I'm piecing together from your comments suggests that you may use tab characters in a different way than most people seem to, so I'd quite like a further explanation of how you use tab characters and how you expect an editor to handle them.
> you may use tab characters in a different way than most people seem to
As far as I'm aware there are three primary and entirely independent uses for tabs. Indentation, field separation, and typesetting. When it comes to typesetting and also to display of fields with a narrow maximum width the concept of a tabstop is useful.
Boneheaded things with tabs was in reference to code editors (where tabs are more or less exclusively used for indentation) most often failing to provide the ability to disable tabstop. In practice this generally hasn't been a point of friction because until fairly recently the most popular languages (ie C & co) didn't support constructs that would lead to adding any indentation outside of the prefix of a line.
Agreed... but see my Lisp example in https://news.ycombinator.com/item?id=49593406 for a place where tabs end up unavoidably ambiguous. Because in that `cond` example the tabs look like they're used for indentation, but they're actually being used for alignment, something that falls more under typesetting than under indentation. A smart editor that has read the Lisp code (note that I'm using "read" in its Lisp meaning, i.e. "parsed into a syntax tree") can make those tab characters correctly align the forms the way you'd want them to be aligned for maximum understanding... but really, you would want space characters, not tab characters, in that context.
So even though in most cases those three uses for tabs are independent, in some languages they get muddled. F# is another language where you may want to align text on line two with the middle of line one, e.g. if you write
Now, that's considered bad style according to https://learn.microsoft.com/en-us/dotnet/fsharp/style-guide/... — and they're entirely write to recommend against that style — but it's legal syntax. And it's probably why https://learn.microsoft.com/en-us/dotnet/fsharp/style-guide/... forbids tab characters entirely in F# code.
(Those two links point to different anchors in the same document, BTW: the HN link shortening is going to make them look identical until you hover over them).
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