Reading binary streams with decoding to Unicode

[Vinay Sajip via Digitalmars-d-learn]

Is there a standardised way of reading over buffered binary 
streams (at least strings, files, and sockets) where you can 
layer a decoder on top, so you get a character stream you can 
read one Unicode char at a time? Initially UTF-8, but later also 
other encodings. I see that std.stream was deprecated, but can't 
see what other options there are. Can anyone point me in the 
right direction?