Hash? validation doesn't work with string keys?

Hi! I’m trying to integrate dry-validation into a project of mine, and I’m noticing that it doesn’t work if you use a string as the key (i.e. { 'example_key' => example_value}. Is this intended? Or is there a way to work with hashes that use this format?

Which schema type did you use? Please provide some code examples.

An example of how the schema was set up would be like this:
Dry::Validation.Schema do
required(:example_hash) { filled? > hash }

Which would be filled in by a hash that is formatted like this: example_hash: { 'a' => 1 }

For string keys you want Dry::Validation.Params do ... end.