Using Dry::Types in Your Application

1. Make Dry::Types available to the application by creating a namespace that includes Dry::Types:

   module Types
    include Dry.Types()
   end
   

2. Reload the environment, & type Types::Coercible::String in the ruby console to confirm it worked:

   Types::Coercible::String
   # => #<Dry::Types::Constructor type=#<Dry::Types::Definition primitive=String options={}>>
   

Creating Your First Type

1. Define a struct's types by passing the name & type to the attribute method:

   class User < Dry::Struct
     attribute :name, Types::String
   end
   

2. Define Custom Types in the Types module, then pass the name & type to attribute:

   module Types
     include Dry.Types()
   
     Email = String.constrained(format: /\A[\w+\-.]+@[a-z\d\-]+(\.[a-z]+)*\.[a-z]+\z/i)
     Age = Integer.constrained(gt: 18)
   end
   class User < Dry::Struct
     attribute :name, Types::String
     attribute :email, Types::Email
     attribute :age, Types::Age
   end
   

3. Use a Dry::Struct as a type:

   class Message < Dry::Struct
     attribute :body, Types::String
     attribute :to, User
   end