WASI stdio (stdin, stdout) API not very useful

What is the problem this feature will solve?

Currently the WASI API only lets you give file descriptors for stdin, stdout and stderr. That's not very useful. In most cases I want to interact with these streams which doesn't seem possible - at least not without a ton of platform specific work - with just file descriptors.

What is the feature you are proposing to solve the problem?

You should be able to pass ReadableStream and WritableStream instead. You can do this when spawning subprocesses.

What alternatives have you considered?

Slightly ludicrously, spawning a new child process that just starts the WASI module and does nothing else seems to be the most reasonable workaround currently, though I haven't tried it.

まず、既存の WASI stdio API と、issue で説明されているサブプロセスの生成時のストリーム動作を確認します。ReadableStream と WritableStream がファイルディスクリプターをどのように置き換えるか、または補完するかを、互換性と明確な完了基準を含めて定義します。