IEx has tab completion of library functions, just like IRB. To see all the built-in Stream functions, just type
Stream. and hit
TAB, and you'll get output like this:
iex(1) Stream. Reducers chunk/2 chunk/4 chunk_by/2 concat/1 concat/2 cycle/1 dedup/1 dedup_by/2 drop/2 drop_while/2 each/2 filter/2 filter_map/3 flat_map/2 interval/1 into/3 iterate/2 map/2 reject/2 repeatedly/1 resource/3 run/1 scan/2 scan/3 take/2 take_every/2 take_while/2 timer/1 transform/3 transform/4 unfold/2 uniq/2 with_index/2 zip/2
This is a nice feature when you're experimenting in the REPL.
h/t Micah CooperTweet