[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Leancase](https://evolu.dev/docs/api-reference/common/Leancase) › LeancasedString

```ts
type LeancasedString = string & import("./Brand.ts").Brand<"Leancased">;
```

Defined in: [packages/common/src/Leancase.ts:115](https://github.com/evoluhq/evolu/blob/bc4578a260dd15d5bbf94b83765ca05984d194cb/packages/common/src/Leancase.ts#L115)

**`Experimental`**

A [String](https://evolu.dev/docs/api-reference/common/Type/variables/String) in leancase.

This Type validates that a string is already in leancase; it does not modify
the value. Use [leancase](https://evolu.dev/docs/api-reference/common/Leancase/functions/leancase) to convert a string.

### Example

```ts
import { assertErr, assertOk, LeancasedString } from "@evolu/common";

assertOk(LeancasedString.fromUnknown("hello. world"), "hello. world");
assertErr(LeancasedString.fromUnknown("Hello. World."));
```