Welterweight Go: Boxing, Structural Subtyping, and Generics

Raymond Hu

doi:10.1145/3776721

Welterweight Go: Boxing, Structural Subtyping, and Generics

2026-01-01

0

PRE

AI

DOI：10.1145/3776721

Original request for help

Save

Abstract

En 中文

Go's unique combination of structural subtyping between generics and types with non-uniform runtime representations presents significant challenges for formalising the language. We introduce WG (Welterweight Go), a core model of Go that captures key features excluded by prior work, including underlying types, type unions and type sets, and proposed new features, such as generic methods. We also develop LWG, a lower-level language that models Go's runtime mechanisms, notably the distinction between raw struct values and interface values that carry runtime type information (RTTI). We give a type-directed compilation from WG to LWG that demonstrates how the proposed features can be implemented while observing important design and implementation goals for Go: compatibility with separate compilation, and no runtime code generation. Unlike existing approaches based on static monomorphisation, our compilation strategy uses runtime type conversions and adaptor methods to handle the complex interactions between structural subtyping, generics, and Go's runtime infrastructure.

Keywords:

Go

Generics

Boxing

Welterweight Go: Boxing, Structural Subtyping, and Generics

Abstract

Journal

Organization