# SetIs\[A: A\]
<span class="source-link">[[Source]](src/collections/set.md#L3)</span>
```pony
type SetIs[A: A] is
  HashSet[A, HashIs[A!] val] ref
```

#### Type Alias For

* [HashSet](collections-HashSet.md)\[A, [HashIs](collections-HashIs.md)\[A!\] val\] ref

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