left-pad (https://www.npmjs.com/package/left-pad) is the quintessential shallow module. A domain specific language is a very deep module.

Their main sell is not a DSL as such but many small general components and combinators to combine them

I am not sure who is the target audience of that book, but I think it's not practical. I respect the authors but the book has gone overboard with flexibility at the expense of good abstractions and design