scheme48(1)                OpenBSD Reference Manual                scheme48(1)



NAME
       scheme48 - a Scheme interpreter

SYNOPSIS
       scheme48 [-i image] [-h heapsize] [-a argument]

DESCRIPTION
       scheme48 is an implementation of the Scheme programming language as
       described in the 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.

       The 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 console.

       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 -h 0.

       The ,dump and ,build commands put heap images in files.  The -i option
       causes the initial heap image to be taken from file image.  The -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
            > ,exit
            $ scheme48 -i foo.image -a mumble
            mumble
            $

FILES
       /usr/local/lib/scheme48/scheme48vm      the virtual machine.

       /usr/local/lib/scheme48/scheme48.image  the default image.



                                                                   scheme48(1)
