— Scheme Procedure: read-options-interface [setting]
— Scheme Procedure: eval-options-interface [setting]
— Scheme Procedure: print-options-interface [setting]
— Scheme Procedure: debug-options-interface [setting]
— Scheme Procedure: evaluator-traps-interface [setting]
— C Function: scm_read_options (setting)
— C Function: scm_eval_options_interface (setting)
— C Function: scm_print_options (setting)
— C Function: scm_debug_options (setting)
— C Function: scm_evaluator_traps (setting)

If one of these procedures is called with no arguments (or with setting == SCM_UNDEFINED in C code), it returns a list describing the current setting of the read, eval, print, debug or evaluator traps options respectively. The setting of a boolean option is indicated simply by the presence or absence of the option symbol in the list. The setting of a non-boolean option is indicated by the presence of the option symbol immediately followed by the option's current value.

If called with a list argument, these procedures interpret the list as an option setting and modify the relevant options accordingly. [FIXME — this glosses over a lot of details!]

If called with any other argument, such as 'help, these procedures return a list of entries like (OPTION-SYMBOL DEFAULT-VALUE DOC-STRING), with each entry giving the default value and documentation for each option symbol in the relevant set of options.