LS48(1)

NAME
LS48 - a Scheme interpreter

SYNOPSIS
LS48 [-i image] [-h heapsize] [-a argument]

DESCRIPTION
LS48 is an implementation of the Scheme programming language as described in the Revised^4 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. LS48 is a shell script that starts the virtual machine with an image that runs in a Scheme command loop.

The LS48 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 -h option causes heapsize words to be allocated for both semispaces of the copying garbage collector. 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 6000000 (actually a little more, to account for the initial heap image and breathing room).

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
     $ LS48 -i foo.image -a mumble
     mumble
     $

FILES

LLIB/scheme48vm
    the virtual machine.

LLIB/LS48.image
    the default image.

BUGS
Procedure calls with more than 63 explicit arguments might not work.