Data and types

Central to how Crochet works is the idea of a type. What Crochet calls a “type” is slightly different than what most other languages mean by the term, but that’s because Crochet overloads the term to mean several different things. In this section we’ll dive deep into types and their roles.

• Types and data modelling
  • What are types?
  • Type declarations and usage
  • Fields of typed data
    • Global fields
  • Data-less types
  • Singleton types
  • Types as possibilities
  • Abstract types
  • Enumeration types
  • Static types
• Hierarchies of types
  • Modelling possibilities
    • Caveats of a static hierarchy
    • Caveats of an open hierarchy
    • Caveats of field projection
  • Testing classifications
• Traits
  • Intentionality of implementation
  • Trait relationships
  • Implementing multiple traits
  • Testing for traits
    • Traits in a type hierarchy