This is funny but it cannot be called an implementation of `ed` because it only implements the tiniest fraction of ed. It doesn't have super basic commands like `a` (to append text), or `,p` (to print all lines), or any range support at all, let alone more advanced stuff like regular expressions.

So it's nowhere close to a POSIX-compliant implementation of ed, and not just for trivial reasons like that it cannot read/write files or execute shell commands.