Comment by tosh

> Turns out most of the time it's more like a puzzle to get an (often inefficient) terse implementation by torturing some linear algebra operators.

solutions in APL can be very efficient if they are written in a machine sympathetic way

or in cases where the interpreter can map them onto one

for the curious:

https://aplwiki.com/wiki/Performance

https://www.youtube.com/watch?v=-6no6N3i9Tg (The Interpretive Advantage)

https://ummaycoc.github.io/wc.apl/ (Beating C with Dyalog APL: wc)