Go is moving in a steady pace towards version 2.0. The community is in a fierce discussion on the implementation of generics. In this talk we will review the need and history of generics. Talk about different implementation of generics in other languages, like Java and C++. Finally we will review the current proposal for implementing generics in Go.

1. Generics,
Go

2. Contents
● About Generics
● Current Alternatives
● Solutions in Other Languages
● Go 2 - Contracts Proposition
● Summary

3. About Generics
● Idea was first introduced in ML in 1975
● Increase expressiveness while maintaining type safety
● Reduces the amount of code a developer has to write
● Given N DataStructs and M algorithms, implement only
M times instead of NxM

4. Current Alternatives
● closed set of builtin generics
● interface{}, boxing/unboxing; collection/list
● Reflection
● Code generation

5. C++ Implementation
● Compile Time Macro Expansion
● Slow compilation
● Code Bloat
● Type checking Errors are hard to understand

6. Java Implementation
● Implemented using Implicit boxing
● Slow execution
● Uses type erasure
● Cannot use reflection, type safety brakes at runtime

7. Solutions in Other Languages
● There are at least 20 different implementations
● Package level templates
● Compile-time function evaluation
● Runtime specialization

8. Go 2 - Contracts Proposition
func Stringify(type T)(s []T) (ret []string)
{
for _, v := range s {
ret = append(ret, v.String())
}
return ret
}

9. Go 2 - Contracts Proposition
contract stringer(T) {
T String() string
}

10. Contracts Proposition
● Values of type parameters are not boxed
● Compiler will use the contract to validate the type
● Function argument type inference
● Predefined contract types for comparable

11. slow programmers,
slow compilers,
or slow execution times
Summary

12. Go For Life!
@edkvm Medium

13. Current Go 2 Generics Proposal:
https://go.googlesource.com/proposal/+/master/design/go2draf
t-contracts.md
Feedback page:
https://github.com/golang/go/wiki/Go2GenericsFeedback
Generics Problem overview:
https://github.com/golang/proposal/blob/master/design/go2draf
t-generics-overview.md
Generics in Go 2:
https://www.youtube.com/watch?v=WzgLqE-3IhY
Comparing generics in in various programing languages:
https://web.archive.org/web/20170812055356/http://www.crest.
iu.edu/publications/prints/2003/comparing_generic_programmi
ng03.pdf
Summary of Go Generics Discussions:
https://docs.google.com/document/d/1vrAy9gMpMoS3uaVphB3
2uVXX4pi-HnNjkMEgyAHX4N4/view#heading=h.iyar50wffpig
Generics using Code Generation:
https://github.com/cheekybits/genny
Experience Reports:
https://medium.com/@sameer_74231/go-experience-report-for-
generics-google-metrics-api-b019d597aaa4
References