Just to be clear, a Pipe counts as a channel for me; like I said, it requires a goroutine. Don't get me wrong, this is definitely the "right" go implementation, and what GHC does internally with thunks is way worse than goroutines.

The point is it no longer looks so superior to the Haskell version, especially since there were many LOC in the haskell version just defining the Key datatype which go never does.