I'm feeling pretty good about f-strings. They're pretty much a proven concept, combining .format() strings in Python, and expression interpolation in other languages. But for i-strings, I think it would be good if we could gather more actual experience using them. Every potential use case brought up for these so far (translation, html/shell/sql quoting) feels like there's a lot of work needing to be done to see if the idea is actually viable there. It would be a shame if we added all the (considerable!) machinery for i-strings and all we got was yet another way to do it (https://xkcd.com/927/), without killing at least one competing approach (similar to the way .format() has failed to replace %). It's tough to envision how we could gather more experience with i-strings *without* building them into the language, but I'm really hesitant to add them without more experience. (This is the "new on the job market" paradox. :-) Maybe they could be emulated using a function call that uses sys._getframe() under the covers? Or maybe it's possible to cook up an experiment using other syntax hooks? E.g. the coding hack used in pyxl ( https://github.com/dropbox/pyxl).[1] Some specific thoughts: - In HTML, there are multiple different ways that stuff needs to be quoted, depending on context, e.g. as element text, or as an attribute value, or inside <script></script>. My (limited) experience with pyxl at Dropbox also suggests that html often is constructed programmatically in multiple stages, so it's important to be able to include already-interpolated html fragments into another html block. - In SQL the evaluation of $N is often built into the SQL parser. - Honestly, subprocess.call(i'echo $filename') looks like it's referencing an environment variable, not a variable in the Python code. [1] I am not endorsing pyxl -- its use is currently controversial at Dropbox. But its "coding: pyxl" hack is easily adapted for other syntax experiments (e.g. https://github.com/JukkaL/mypy/tree/master/mypy/codec). -- --Guido van Rossum (python.org/~guido)