scheme48 is an implementation of the Scheme programming language as described in
Revised^5 Report on the Algorithmic Language Scheme. A runnable system requires two parts, an executable program that implements
the Scheme 48 virtual machine, and an image that is used to initialize
the store of the virtual machine.
scheme48 is a shell script that starts the virtual machine with an image that runs
in a Scheme command loop.
scheme48 command loop reads Scheme expressions,
evaluates them, and prints their results.
It also executes commands, which are identified by an initial comma character.
Type the command
,help to receive a list of available commands.
The meaning of the
-h option depends on the type of garbage collector that was chosen at
configuration time. If
heapsize is a positive number, it specifies
the number of words that can be live at any given time.
One word is four bytes. Cons cells are currently 3 words,
so if you want to make sure you can allocate, say, a million cons
cells, you should specify
-h 3000000 (actually a little more, to account for the initial heap
image and breathing room).
If you specify a
maximum smaller than the memory needed to load the image file, the
maximum is increased accordingly and a message is written to the
For the BIBOP garbage collector,
heapsize may be 0. This means the heap will
possibly keep growing until your system runs out of memory. Because of
this risk, a warning message is written to the console if you specify
,build commands put heap images in files.
-i option causes the initial heap image to be taken from file
-a option causes a list of strings to be passed as the argument
to an image generated using the
,build command. The first argument to
,build is a procedure that is passed
the arguments following
-a and which should return an integer (which is the
return value of the Scheme 48 process).
> ,build (lambda (a) (display a) (newline) 0) foo.image
$ scheme48 -i foo.image -a mumble