System Commands

REPL Command: gc

Garbage collection.

REPL Command: statistics

Display statistics.

REPL Command: option [name] [exp]

With no arguments, lists all options. With one argument, shows the current value of the name option. With two arguments, sets the name option to the result of evaluating the Scheme expression exp.

REPL Command: quit

Quit this session.

Current REPL options include:


The options used when compiling expressions entered at the REPL. See Compiling Scheme Code, for more on compilation options.


Whether to interpret or compile expressions given at the REPL, if such a choice is available. Off by default (indicating compilation).


A customized REPL prompt. #f by default, indicating the default prompt.


A procedure of two arguments used to print the result of evaluating each expression. The arguments are the current REPL and the value to print. By default, #f, to use the default procedure.


Whether value history is on or not. See Value History.


What to do when an error happens. By default, debug, meaning to enter the debugger. Other values include backtrace, to show a backtrace without entering the debugger, or report, to simply show a short error printout.

Default values for REPL options may be set using repl-default-option-set! from (system repl common):

Scheme Procedure: repl-default-option-set! key value

Set the default value of a REPL option. This function is particularly useful in a user’s init file. See The Init File, ~/.guile.