dry_markup.rb

require 'dry-struct'

module Types
  include Dry::Types.module
end

class Button < Dry::Struct
  attribute :text, Types::String
end

class Markup < Dry::Struct
  attribute :keyboard, Types::Strict::Array.member(Types::Strict::Array.member(Button))
end

mark = Markup.new(
  keyboard: [
    [{ text: '1st button text' }, { text: '2nd button text' }],
    [{ text: '3rd button text' }]
  ]
)
=> #<Markup keyboard=[[#<Button text="1st button text">, #<Button text="2nd button text">], [#<Button text="3rd button text">]]>

Markup.schema
=> {:keyboard=>#<Dry::Types::Constrained type=#<Dry::Types::Array::Member primitive=Array options={:member=>#<Dry::Types::Constrained type=#<Dry::Types::Array::Member primitive=Array options={:member=>Button} meta={}> options={:rule=>#<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#type?> options={:args=>[Array]}>} rule=#<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#type?> options={:args=>[Array]}>>} meta={}> options={:rule=>#<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#type?> options={:args=>[Array]}>} rule=#<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#type?> options={:args=>[Array]}>>}