pfn

because gradle is slow, and the dsl is a disaster compared to sbt

actually, the latter is far more readable without markup making my eyes bleed.

I generally prefer gradle's method of 'com.foocorp:foo:1.2' but that isn't acceptable statically. scala string interpolators could make it a thing, though.

permutation, mapping, zipping and filtering are all completely idiomatic scala.

There is next to no cognitive load in this 4-line solution. Brute-force attack on every permutation. I would say that anyone find there to be an excessive cognitive load would be someone that is not familiar with scala nor functional programming.