Tabs

• One indent == one character, so you wont find yourself mashing arrow keys to navigate through loads of spaces
• All decent editors support changing the width of a tab (whereas for spaces this is a bit more niche)
  • If the editor starts arbitrarily changing the width of spaces, then it defeats the argument of using spaces for alignment
  • No more arguments over space width 🥳
  • Visually impaired users with large font sizes can have a low indent width, so they can see everything properly
• Barring some weird REPLs and small web based editors, just about every IDE will support tabs.

Spaces

• The tab default of 8 characters is a bit much for a single layer of indentation
  • Git{hub,lab,ea} will default to displaying them as 8 characters¹
  • If your editor supports using the tab key to insert spaces, then it probably supports changing the tab width
• The variable tab width makes it hard to align things
  • Depending on context it makes it easier to align things, so this argument is bs
• You won’t find yourself fighting against the tooling that you are using (especially for niche programming environments like web IDE’s or embedded REPL’s) if tabs have a special meaning
  • Is it really worth it to degrade your choice of indentation just to appease some cruddy tooling?
• Some lanuguages² and style guides³ default to or demand using spaces for formatting
  • This isn’t really valid, as some projects and languages default to using tabs, namely Go and Linux.
• Good for alignment, as all spaces will have a consistent size

Conclusion

It should go without saying that, for existing projects, you should just use the established convention. The only thing worse than 3 spaces of indentation is x spaces of indentation, where x is a arbritrary unsigned intiger that can change depending on which file you are looking at.

Though in the above comparison, spaces had more points than tabs, spaces also had more points refuting itself. In sum, tabs are better. For indentation, the width is about as important as the editor font or theme. Tabs are therefore more suited for indentation (as they tend to come with a customiseable width). As for alignment, use spaces, not tabs⁴.

Some people like an indent width of 2, others 4, some 8 or 6 or even 3- cut the crap, use a tab; let users decide how many spaces that tab represents.

If you can, use an auto formatter! I can write the most horifically wrong code in the world and rustfmt will clean it up for me.⁵

Further reading

This excellent reddit thread has some nice thoughts on the benefits of spaces, including a back-and-forth between pro-space and pro-tab people.