A one-liner alternative for hash-only cases can be implemented using Enumerable#reduce: root = {} [:a, :b, :c].reduce(root){@1[@2]||={}}[:d] = 'E' # root => {:a=>{:b=>{:c=>{:d=>"E"}}}}

I think the issues/problems specified in the comments are not present with a Hash-only implementation. :) I would be supportive of re-considering this feature just for use with a Hash, where I believe 80% of the real-life use cases would (and do) exist. I have encountered this need before in the wild, but not with Arrays.

While Trailblazer offers you abstraction layers for all aspects of Ruby On Rails, it does not missionize you. Wherever you want, you may fall back to the "Rails Way" with fat models, monolithic controllers, global helpers, etc. This is not a bad thing, but allows you to step-wise introduce Trailblazer's encapsulation in your app without having to rewrite it.

"doesn't work" is meaningless

I don't think we want the cookbook to become a collection of tutorials regarding how to use certain libraries and tools with svelte. A set of more generic recipes or deep dives into topics would probably serve people better and have broader application.

The feature is highly likely to be implemented, the API and implementation are the only real topics of discussion right now.