Some APL environments such as ngn/apl[0] allow tab completion like |o<tab> results in ⌽. This is probably available on tryapl.org too, but I can't test it when it's down :/. It may also be available in the full dyalog apl product and IDE.
(not parent) personally I would like to see [trains](https://aplwiki.com/wiki/Tacit_programming#Trains) in more languages, though the way they are implemented in APL is pretty spotty (e.g. the length of a train changes its semantics)
I agree, but you have to take extensibility into account. You either have an extensible language and extend it[0], you make it an array language to the core, or you just have a few slightly convenient functions (not a language). (I don't have enough experience to judge which category Pandas / numpy are in)
EDIT: see https://news.ycombinator.com/item?id=27462828 too
[0]: https://github.com/abrudz/ngn-apl