alt Hacker NewsSurely tabs are only ambiguous if one considers the point of indentation to be to align things visually in relation to each other, as opposed to just being, y'know, indented.
Besides, I'm sure many people would look at your Scheme snippet and argue that it's not really about indentation as much as alignment of the subforms, because in a Lisp those two things are basically equivalent, and that the distinction between indentation and alignment is mostly a thing for the curly-brace or otherwise ALGOL-esque languages like Pascal or in this case Python. And in those cases the use of "tabs for indentation, spaces for alignment" is fairly popular although I don't frankly know if many editors actually support that.
I do however think that this whole discussion of spaces Vs tabs is pretty asinine and mostly just stems from people just wanting to align code text visually across lines. It's the same way people insist on monospaced fonts even though one could easily make the argument that proportional fonts are easier to read. Oh well, even I'm not _that_ deprived.
> the use of "tabs for indentation, spaces for alignment" is fairly popular although I don't frankly know if many editors actually support that.
It all works swimmingly until you introduce a nested scope (indentation, tabs) in the middle of an aligned scope (spaces). At that point it still works in the sense that everything is correctly aligned however depending on the editor the tabs might not all have the same width if you aren't able to disable tabstop.
So it isn't generally recommended for lisps in practice (because most common editors will correctly align any given block but when considered in whole the formatting will be inconsistent) but poses near zero problems for most c like languages. (If you're determined you can manage to create problems in a c like by nesting an anonymous lambda within an aligned list of statements or similar such shenanigans. However pretending that python or c++ is a lisp is generally frowned upon so in practice all tabs can be expected to appear to the left of any spaces.)