Go is a popular statically-typed industrial programming language. To aid the type safe reuse of code, the
recent Go release (Go 1.18) published early 2022 includes bounded parametric polymorphism via generic types.
Go 1.18 implements generic types using a combination of monomorphisation and call-graph based
dictionary-passing called hybrid. This hybrid approach can be viewed as an optimised form of monomorphisation that
statically generates specialised methods and types based on possible instantiations. A monolithic dictionary
supplements information lost during monomorphisation, and is structured according to the program’s call
graph. Unfortunately, the hybrid approach still suffers from code bloat, poor compilation speed, and limited
code coverage.

In this paper we propose and formalise a new non-specialising call-site based dictionary-passing translation.
Our call-site based translation creates individual dictionaries for each type parameter, with dictionary
construction occurring in place of instantiation, overcoming the limitations of hybrid. We prove it correct using
a novel and general bisimulation up to technique. To better understand how different generics translation
approaches work in practice, we benchmark five translators, Go 1.18, two existing monomorphisation
translators, our dictionary-passing translator, and an erasure translator. Our findings reveal several suggestions for
improvements for Go 1.18— specifically how to overcome the expressiveness limitations of generic Go and
improve compile time and compiled code size performance of Go 1.18.