Since you are using ¨, ⍵ is a scalar, so you don't need the ∘.

Translated back to J

  ((;'Buzz';'Fizz';'FizzBuzz'"_){~2#.0=3 5|])"0>:i.100

The boxed list in J feels a bit cumbersome compared to mixed arrays in APL.

Fair enough. Like most APL I wrote it backwards until it worked.

Works out-of-the box in GNU APL as well, if someone wants to try it with a free version of APL.

To that end, my K version can be tweaked slightly to work with oK, an open-source interpreter based on k6:

    {(x;"Buzz";"Fizz";"FizzBuzz")@2 2/~3 5!\:x}'1+!20

k6 swapped the argument order of "mod" and made change of base into an overload of "/", rather than a named builtin. See it in action here:

http://johnearnest.github.io/ok/index.html?run=%20%7B%28x%3B...