The implementation in STM works well and certainly ticks the battle-tested box:
https://hackage.haskell.org/package/stm-2.4.4.1/docs/ Control-Concurrent-STM-TChan.html#v:newBroadcastTChan
What does the following comment in the documentation really mean (highlighted by >>><<<)? "Create a write-only TChan <https://hackage.haskell.org/package/stm-2.4.4.1/docs/Control-Concurrent-STM-TChan.html#t:TChan>.
More precisely, readTChan <https://hackage.haskell.org/package/stm-2.4.4.1/docs/Control-Concurrent-STM-TChan.html#v:readTChan> will retry <https://hackage.haskell.org/package/stm-2.4.4.1/docs/Control-Monad-STM.html#v:retry> even after items have been written to the channel.<<< The only way to read a broadcast channel is to duplicate it with dupTChan <https://hackage.haskell.org/package/stm-2.4.4.1/docs/Control-Concurrent-STM-TChan.html#v:dupTChan> ."
-- Saurabh.