A world image, also called a band, is a file that contains a
complete Scheme system, perhaps additionally including user application
code. Scheme provides a method for saving and restoring world images.
The method writes a file containing all of the Scheme code and data in
the running process. The file runtime.com that is loaded by the
microcode is just such a band. To make your own band, use the procedure
Causes a band to be written to the file specified by filename. The optional argument identify controls what happens when that band is restored, as follows:
- not specified
- Start up in the top-level REPL, identifying the world in the normal way.
- a string
- Do the same thing except print that string instead of `Scheme' when restarting.
- the constant
- Restart exactly where you were when the call to
disk-savewas performed. This is especially useful for saving your state when an error has occurred and you are not in the top-level REPL.
- the constant
- Just like
#t, except that the runtime system will not perform normal restart initializations; in particular, it will not load your init file.
To restore a saved band, give the --band option when starting
Scheme. Alternatively, evaluate `(disk-restore filename)',
which will destroy the current world, replacing it with the saved world.
The argument to
disk-restore may be omitted, in which case it
defaults to the filename from which the current world was last restored.