[preact/compact] Suppport react-is

[clyfish]

Describe the feature you'd love to see
Some libraries use react-is to check types of react element.
Will @preact/compat support react-is?
Additional context (optional)
https://www.npmjs.com/package/react-is

// for example
import { isMemo, isFragment } from 'react-is'

[marvinhagemeister]

It's very unlikely that we'll ever support react-is. It relies on very react specific internals that no other third party library needs. If there is a need for something like react-is we'd rather add another entry to our package so that react-is can be aliased to that.

So far we haven't come across libraries checking for the type of react element. Can you share the ones you found?

[clyfish]

@marvinhagemeister antd and react-dnd depend on react-is, and more.

$ npm ls react-is
├─┬ antd@5.2.2
│ └─┬ rc-util@5.28.0
│   └── react-is@16.13.1
└─┬ react-dnd@16.0.1
  └─┬ hoist-non-react-statics@3.3.2
    └── react-is@16.13.1 deduped

[ziongh]

Great that isFragment is implemented! But isMemo is not yet implemented, and that breaks the Antd (and other) packages.