




Returns either a character from the stream, an :eof if the end-of-file is reached, or nil if no input is currently available.
The generic function stream-read-char-no-hang implements read-char-no-hang. It returns either a character read from the stream, or:eof if end-of-file is reached, or nil if no input is available. The default method provided by fundamental-character-input-stream simply calls stream-read-char which is sufficient for file streams, but interactive streams should define their own method.
LispWorks User Guide and Reference Manual - 20 Sep 2017