A Practical Guide to Generics in Go

Go 1.18 introduced generics, one of the most anticipated features in the language’s history. Here’s how to use them effectively.

Basic Syntax

func Min[T int | float64](a, b T) T {
    if a < b {
        return a
    }
    return b
}

Type Constraints

Instead of listing types inline, use an interface as a constraint:

type Number interface {
    int | int64 | float64
}

func Sum[T Number](nums []T) T {
    var total T
    for _, n := range nums {
        total += n
    }
    return total
}

When to Use Generics

• Writing reusable data structures (slices, maps, trees)
• Utility functions that work with multiple numeric types
• Avoiding interface{} / any with type assertions

When NOT to Use Generics

• When a simple interface would work
• When you’re only using one or two concrete types
• When generics make the code harder to read

Conclusion

Generics are a powerful addition to Go, but they should be used sparingly. Remember the Go proverb: clear is better than clever.