[WhiteRice]

I didn’t see it in the article so I thought I would add,

The actual apl implementation: +/age>17

Apl implementation of taking the length(shape) of the filtered list: ⍴(age>17)/age

[Jtsummers]

It's in there but near the end (80% or so of the way down the page). The article would benefit from moving that to the top and drawing the comparison to the APL code earlier.