[Wezl]

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.

EDIT: see https://news.ycombinator.com/item?id=27462828 too

[0]: https://github.com/abrudz/ngn-apl