Type Theory

Type theory is the study of types.

Types have a cardinality, which is the number of possible values within that type.

References

• Book: Thinking with types

Backlinks

• Types have a cardinality
  • In type theory a type has a cardinality. The cardinality for a given type is the number of possible values. A cardinality can be finite or infinite. A pair of types with the same cardinality will always be isomorphic.
• The void type is called 'never' in TypeScript
  • Although TypeScript has a void keyword it's really another word for undefined for historical reasons - it isn't the void from type theory.
• A type describes a set of possible values
  • In type theory, a type describes a set of possible values. This is usually used to declare what is possible to exist within a variable.
• Void is impossible to construct
  • In type theory, void is a type with no elements. This means that it is impossible to construct a void type.