PowerShell classes still can't create value types

Steps to reproduce

Try to implement any interfaces that is intended to be implemented in terms of yourself, E.g. IEquatable, IComparable:

class ServerName : Object, System.IEquatable[ServerName] {
    [string]$ComputerName
    [bool] Equals([ServerName]$other) {
        return $this.ComputerName.Equals($other.ComputerName);
    }
}

Expected behavior

I should be able to write IEquatable<T> and IComparable<T> classes 

Actual behavior

A runtime compile error:

An error occurred while creating the pipeline.
+ CategoryInfo          : NotSpecified: (:) [], ParentContainsErrorRecordException                                                                 + FullyQualifiedErrorId : RuntimeException                                  

Environment data

Any version of PowerShell since classes were introduced, up to and including 7 Pre 4

[JustinGrote]

@SeeminglyScience thanks. Believe it or not it totally worked 😃 Full code:

using namespace Microsoft.Management.Infrastructure
class CimObserver : System.IObserver[CimInstance] {
    [void] OnNext(
        [CimInstance]$ciminstance
    ) {
        write-host -fore green $cimInstance
    }
    [void] OnError([Exception]$Exception) {throw $exception}
    [void] OnCompleted() {$this.Unsubscribe()} 
}
$query = (new-cimsession).QueryInstancesAsync('root/cimv2','WQL','SELECT * FROM Win32_ComputerSystem')
$observer = new-object CimObserver
$query.subscribe($observer)

Outputted the textual representation in green to the host.

[SeeminglyScience]

@JustinGrote Method names are case sensitive for declaration:

using namespace Microsoft.Management.Infrastructure

class CimObserver : IObserver[CimInstance] {
    [void] OnNext([CimInstance] $value) {}
    [void] OnError([Exception] $exception) {}
    [void] OnCompleted() {}
}

Though be aware that it’s likely that OnNext will be called on a thread without a default runspace. If that’s the case, the method will just throw.