element-type—a type specifier.
The default is
string-stream—an output string stream.
an output string stream that accepts characters
and makes available (via
a string that contains the characters that were actually output.
The element-type names the type of the elements of the string; a string is constructed of the most specialized type that can accommodate elements of that element-type.
(let ((s (make-string-output-stream))) (write-string "testing... " s) (prin1 1234 s) (get-output-stream-string s)) → "testing... 1234"