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Since Scheme48's operation revolves about an image-based model, these commands provide a way to save heap images on the file system, which may be resumed by invoking the Scheme48 virtual machine on them as in Running Scheme48.
,build evaluates resumer, whose value should be a unary procedure, and builds a heap image in filename that, when resumed by the virtual machine, will pass the resumer all of the command-line arguments after the -a argument to the virtual machine. The run-time system will have been initialized as with usual resumers, and a basic condition handler will have been installed by the time that the resumer is called. On Unix, resumer must return an integer exit status for the process. ,dump dumps the Scheme48 command processor, including all of the current settings, to filename. If message is passed, it should be a string delimited by double-quotes, and it will be printed as part of the welcome banner on startup; its default value, if it is not present, is
"(suspended image)"
.