A modern programming language that makes developers happier.

kotlinlang

Klutter release `1.20.0` is on the way with:

```
* BREAKING CHANGE:  from 1.19.x renamed `asImmutable()` to `asReadOnly()`
* BREAKING CHANGE:  from 1.19.x renamed `Immutable*` collection wrappers to `ReadOnly*`
* Added marker interface ReadOnly to the read only collection wrappers
* For List, Map and Set added extensions `toImmutable()` which makes a copy first then protects the items from change by wrapping with `ReadOnly*` wrappers.  Only cruel reflection tricks can break them.
* Adding `equals`, `hashCode` and `toString` for `ReadOnly*` collections
```