— Function: environment-variable name

environment-variable returns the environment variable identified by name, or nil if one does not exist. name can either be a symbol or a string.

setf environment-variable sets the environment variable identified by name to value. Both name and value can be either a symbols or strings. Signals an error on failure.

— Function: environment

environment returns the current environment as an assoc-list. setf environment modifies the environment its argument.

Often it is preferable to use setf environment-variable and makunbound-environment-variable to modify the environment instead of setf environment.

— Function: makunbound-environment-variable name

Removes the environment variable identified by name from the current environment. name can be either a string or a symbol. Returns the string designated by name. Signals an error on failure.