# types.optional

## Summary

This RFC proposes adding a new method to the `types` library in type functions, that provides a shorthand for `types.unionof(type, types.singleton(nil))`

## Motivation

Currently its annoying to have to always type `types.unionof(meow, types.singleton(nil))` to make a optional type, this leads to having the following appear in codebases that make use of optional types a lot in type functions:

```luau
type function optional(type)
	return types.unionof(type, types.singleton(nil))
end
```

## Design

As a solution, a new method to the `types` library should be added called `optional`. This new method will act the same as `types.unionof(type, types.singleton(nil))`.