I've been writing Ruby for 20+ years and "unless" (the whole language, actually) immediately clicked for me when I first learned it.
That said, I only use it in 2 cases:
* as a trailing condition (do_something unless this), mainly for early returns
* as the only arm of a multi-line block (unless this ... end, no "else" blocks - Rubocop would yell at me anyway)
And then only if the condition is either a simple value, or a combination of simple values (this && that, this || that).
That's it. Never had a problem with double negatives or accidentally inverting the logic.
This is basically how I use unless too. Complex conditions are complicated enough to grasp without inflicting an unless on me. But for simple cases it is a nice to have feature.
Of course one can avoid it at all but of course one cannot avoid to spend time on it when reading somebody's else code.
FWIW HN does not support markdown lists (or markdown anything other than emphasis and code blocks really), you need to add an empty line between your “list items” so the comment parser treats them as separate paragraphs instead of munging them together as just one.
That said, I only use it in 2 cases:
* as a trailing condition (do_something unless this), mainly for early returns * as the only arm of a multi-line block (unless this ... end, no "else" blocks - Rubocop would yell at me anyway)
And then only if the condition is either a simple value, or a combination of simple values (this && that, this || that).
That's it. Never had a problem with double negatives or accidentally inverting the logic.