Next: Built-in Parameters Up: Threads and Namespaces Previous: Keywords

# Parameters

A parameter is a thread-specific setting, such a the current output port or the current directory for resolving relative pathnames. A parameter procedure sets and retrieves the value of a specific parameter. For example, the `current-output-port` parameter procedure sets and retrieves a port value that is used by `display` when a specific output port is not provided. Applying a parameter procedure without an argument obtains the current value of a parameter in the current thread, and applying a parameter procedure to a single argument sets the parameter's value in the current thread (and returns void). For example, `(current-output-port)` returns the current default output port, while `(current-output-port p)` sets the default output port to p.

- Built-in Parameters
  - Current Directory
  - Ports
  - Parsing
  - Printing
  - Language
  - Read-Eval-Print
  - Loading
  - Libraries
  - Exceptions
  - Breaks
  - Custodians
  - Exiting
  - Random Numbers
- Parameter Utilities