Background: turns out that the string prefix was the only ASCII syntax left in Python3, that's why it was chosen. The name "eff string" makes me cringe, but once it stuck there was no stopping it.
That explains why you're all over this post ;)
Fantastic feature, though. Really. Thanks!
Out of curiosity, what name would you have preferred over "f-strings"? "Format strings"? "Interpolation strings"? "I-will-evaluate-expressions-in-curly-braces strings"?
What to call it? Anything I guess. String interpolation is what it is called elsewhere. But the f prefix is what everyone sees, though as mentioned, it is only an implementation detail because other forms of syntax were already spoken for. I personally chose f for "format."
Early on Guido changed the scope to include expressions as well. People were already starting to say "eff string" so I changed my proposal to "e-string" for "expression." I also like the sound of it better, sounds like email, etc. But Guido (and Eric) decided to stick with f. Maybe because Guido learned English later he doesn't realize how unfortunate it sounds. But, years later we use the "iPad" and forget it sounds like a feminine napkin. So, no big deal in the end.