Future_unix.PipeSourceDiscard one item from the pipe. Do nothing if pipe is already fully consumed. Difference from Async: This function is not defined.
Like read but doesn't consume the item. Difference from Async: This function is not defined. We don't call this function peek because that is already another function in Async, which has different semantics.
val fold :
'a Reader.t ->
init:'accum ->
f:('accum -> 'a -> 'accum Deferred.t) ->
'accum Deferred.t