The proposal is not finished yet (and might never been). Pessimism aside, there is a whole issue on why it was decided on following up with Hack's implementatio

The proposal is not finished yet (and might never been). Pessimism aside, there is a whole issue on why it was decided on following up with Hack's implementation [1]. You can always give your input on such decisions, the % token is still being "bikeshedded"[2] (is that a word?), and there's still a possibility of making follow-ups proposals that could implement some F#-esque implementation [1]: https://github.com/tc39/proposal-pipeline-operator/issues/221 https://github.com/tc39/proposal-pipeline-operator/issues/22... [2]: https://github.com/tc39/proposal-pipeline-operator/issues/91 https://github.com/tc39/proposal-pipeline-operator/issues/91