Unlocking the Power of Generics in Go
What are Go Generics?
Every statically typed language has generics in one form or another. Generics offer a new way to express type constraints in Go code, enabling the creation of libraries or functions that operate on arbitrary types or values. The primary goal of generics in Go is to avoid boilerplate code or duplication of logic.
The Problem Before Generics
One of Go’s key distinguishing features is its approach to interfaces, which are targeted at code reuse. However, Go already supported a form of generic programming via the use of empty interface types. This method did not support code reuse, and interfaces had to be written with switch cases for every type.
A Brief History of Go Generics
Generics support has always been one of the top problems to fix in the language. The initial design draft for Go generics introduced contracts, which aimed to validate a set of type arguments to a function and the methods that can be called on those types. However, the design was later simplified to use only interface types, as contracts could be represented as a set of interfaces.
Go Generics Today: Bounded Type Parameters
The type parameters proposal for adding generic programming to Go emphasizes optional type parameters or parameterized types. Type parameters are defined using constraints, and interface types act as constraints for type parameters. With interface types, additional types can be added to limit the set of types that may satisfy a given constraint.
Generic Syntax in Go
Functions can have optional type parameters, and types can have a type parameter list. Each type parameter can have an optional type constraint. The any constraint is equivalent to an empty interface type interface{}.
Examples of Functions Using Go Generics
Let’s review some examples of how we might write a generic function in Go today. We can write a min() function that works for both integer and floating-point types without having to explicitly write them based on the types. We can also sort a slice of any type and check if a slice contains a value.
Why We Need Go Generics
Generic programming enables the representation of algorithms and data structures in a generic form, with concrete elements of the code (such as types) factored out. Generics in Go make it easier to write functions once to use everywhere, allowing for greater scalability and easier handling of a growing codebase.
When to Use Generics in Go
You should use Go generics if you are struggling to implement a solution that requires a singularity of behavior for different data types. You should also use Go generics when writing functions that operate on container types like maps, slices, channels, or any other general-purpose data structure.
When Not to Use Generics in Go
You should not use Go generics when calling a method on a type argument. Instead, use an interface type. Also, don’t use Go generics when performing different operations for each type, even within method sets. In this case, use Go’s reflection API instead.
Conclusion
Generics make Go safer, more efficient to use, and more powerful. By unlocking the power of generics in Go, we can implement many problems as functions that would apply to different types and use previously debugged, optimized, and efficient packages or libraries.