<p><span class="h-card" translate="no"><a href="https://mastodon.social/@mcc" class="u-url mention">@<span>mcc</span></a></span> ok so i think i figured out how to do it, but it's... weird</p><p>i think you have to *consume* the string in the indexing operation, embed it into the index, and then return a new, lesser-capable index for further operations</p><p>so the outermost index becomes the one you can mutably poke the string through</p><p>now... what happens if you want to use non-outermost one? i think you need basically forth's swap/rot/roll/etc...</p>