Type Constructor

Definitions

1. A type-level function that takes one or more type arguments and produces a concrete type — for example, `List` is a type constructor that, when applied to `Int`, produces the concrete type `List<Int>`. In Haskell's kind system, a type constructor has kind `* -> *`, distinguishing it from fully applied types of kind `*`.

   In plain English: A blueprint for types that needs to be filled in with a specific type before it becomes a usable type, like a generic container that needs to know what it contains.

   Example: "Option is a type constructor — it's not a complete type until you give it a parameter like Option<String>."

Related Terms

• Lambda Calculus
• Forall
• Monomorphization
• Parser Combinator
• Persistent Data Structure
• Point-Free Style
• Term Rewriting
• Transducer