Generics in Practice

Why a Set Is a Good Example

A set is a collection where each value either exists or does not exist. No duplicates matter. That makes it great for jobs like tags, feature flags, permissions, service names, or supported regions.

It is also a perfect generic example because the behavior stays the same no matter what you store. A set of strings and a set of integers need the same operations: add, remove, check membership, combine, and find overlap.

The Complete Set Type

Let's build the full thing, not a half-example. This small library is enough to use in real programs.

Why comparable Is Required

A set needs to check whether a value is already present and needs to use values as map keys. In Go, map keys must be comparable. That is why the set is Set[T comparable], not Set[T any].

This is a great example of a constraint matching the real job. We are not using comparable because it looks official. We are using it because the data structure literally depends on comparability to function.

Using the Set with Real Data

Let's treat these sets as technology tags on two engineering skill clusters. One cluster is backend-focused. The other is reliability-focused. We want to know what they share and what the combined toolkit looks like.

This is the kind of thing generics are excellent at: building one small, solid tool you can reuse with different real data sets without rewriting the data-structure logic every time.

Tracing Union and Intersection

Quiz

Practice

Summary

• A generic set is a strong real-world example because the structure and operations stay the same across many value types.
• comparable is required because sets depend on map keys and equality checks.
• Methods like Add, Remove, Contains, Union, and Intersection form a small but genuinely useful utility library.
• Extra helpers can use stronger constraints only when needed, like SortedValues[T cmp.Ordered].
• Generics are at their best when they remove repetition from a stable abstraction without hiding the underlying logic.