Reference: PLT Scheme

1`` | Language Model
2`` | Syntactic Forms
3`` | Datatypes
4`` | Structures
5`` | Classes and Objects
6`` | Units
7`` | Contracts
8`` | Pattern Matching
9`` | Control Flow
10`` | Concurrency
11`` | Macros
12`` | Input and Output
13`` | Reflection and Security
14`` | Operating System
15`` | Memory Management
16`` | Running PLT Scheme
| Bibliography
| Index

On this page:

input-port?
output-port?
port?
close-input-port
close-output-port
port-closed?
current-input-port
current-output-port
current-error-port
file-stream-port?
terminal-port?
eof
eof-object?

Version: 4.0.2
contents index
← prev up next →

##### 12.1.2`` Managing Ports

(input-port? v) → boolean?
v : any/c

Returns #t if v is an input port, #f otherwise.

(output-port? v) → boolean?
v : any/c

Returns #t if v is an output port, #f otherwise.

(port? v) → boolean?
v : any/c

Returns #t if either (input-port? v) or (output-port? v) is #t, #f otherwise.

(close-input-port in) → void?
in : input-port?

Closes the input port in. For some kinds of ports, closing the port releases lower-level resources, such as a file handle. If the port is already closed, close-input-port has no effect.

(close-output-port out) → void?
out : output-port?

Closes the output port out. For some kinds of ports, closing the port releases lower-level resources, such as a file handle. Also, if the port is buffered, closing may first flush the port before closing it, and this flushing process can block. If the port is already closed, close-output-port has no effect.

(port-closed? port) → boolean?
port : port?

Returns #t if the input or output port port is closed, #f otherwise.

(current-input-port) → input-port?
(current-input-port in) → void?
in : input-port?

A parameter that determines a default input port for many operations, such as read.

(current-output-port) → output-port?
(current-output-port out) → void?
out : output-port?

A parameter that determines a default output port for many operations, such as write.

(current-error-port) → output-port?
(current-error-port out) → void?
out : output-port?

A parameter that determines an output port that is typically used for errors and logging. For example, the default error display handler writes to this port.

(file-stream-port? port) → boolean?
port : port?

Returns #t if the given port is a file-stream port (see File Ports), #f otherwise.

(terminal-port? port) → boolean?
port : port?

Returns #t if the given port is attached to an interactive terminal, #f otherwise.

eof : eof-object?

A value (distinct from all other values) that represents an end-of-file.

(eof-object? a) → boolean?
a : any/c

Returns #t is v is eof, #f otherwise.

contents index
← prev up next →