1.1 KiB
Input and Output Ports
A port encapsulates an I/O stream, normally for just one direction. An input port reads from a stream, and an output port writes to a string.
For many procedures that accept a port argument, the argument is
optional, and it defaults to either the current input port or current
output port. For mzscheme, the current ports are initialized to the
process’s stdin and stdout. The current-input-port and
current-output-port procedures, when called with no arguments, return
the current output and input port, respectively.
Examples:
> (display "hello world\n")
hello world
> (display "hello world\n" (current-output-port))
hello world
Ports are created by various procedures that specific to the different
kinds of streams. For example, open-input-file creates an input port
for reading from a file. Procedures like with-input-from-file both
create a port and install it as the current port while calling a given
body procedure.
See [missing] for information about using ports.