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types

Syntax and types​

Typed R keeps a syntax that is deliberately close to standard R. Type annotations are added in a lightweight and readable way, designed to integrate naturally with existing R code.

Types can appear:

  • in variable declarations,
  • in function parameters,
  • in function return types,
  • in structured data definitions.

The design principle is that typed code should still look like R, with minimal syntactic overhead.

Basic types​

Typed R provides explicit basic (primitive) types, which form the foundation of the type system:

  • Numeric types (e.g. integers, floating-point numbers)
  • Boolean values
  • Character strings
  • Missing values

These types allow the compiler to detect invalid operations early, such as applying numeric operations to non-numeric values.

Composite types​

In addition to basic types, Typed R supports composite types to model more complex data:

  • Vectors with guaranteed element types
  • Lists with typed elements
  • Records (structured objects with named and typed fields)
  • Data frames with explicit schemas

Composite types make data structures self-documenting and safer to manipulate, especially in large data-processing pipelines.

Type inference​

Typed R features type inference, meaning that explicit type annotations are not always required.

When possible, the compiler automatically infers types based on:

  • literal values,
  • expressions,
  • function bodies,
  • usage context.

This allows developers to write concise code while still benefiting from static type checking. Explicit types can be added incrementally where clarity or safety is critical.