Basetypes

Basetypes, or base types, are the fundamental, non-composite types provided by a programming language or type system. They are defined directly by the language specification rather than in terms of other types, and they serve as the primitive building blocks from which more complex types are constructed.

Key characteristics of basetypes include their fixed representation and well-defined operations. They typically include numeric types (such as integers and floating-point numbers), boolean, character, and sometimes string or date/time types, depending on the language. Basetypes usually support a core set of operations (arithmetic, comparison, conversion) and play a central role in ensuring type safety, since many rules about how values can be used and combined are specified for these primitive kinds.

In most type systems, other types are built from basetypes using type constructors or aggregations. For example, arrays, records, tuples, functions, and generic types are formed by combining basetypes or other types. The relationship between basetypes and derived types often includes rules about subtyping, promotion or coercion, and nullability. Basetypes often have concrete memory representations, which informs performance and optimization decisions in a compiler or runtime.

Different languages may vary in what they count as a basetype. Some treat strings as primitive basetypes, while others implement strings as derived types built from characters. Some languages also differentiate unsigned and signed numeric basetypes, or expose additional primitives for dates, times, or pointers. Across domains, the term basetype generally denotes the core, lowest-level types that underpin a language’s type system.