The Scheme implementation that we'll be using during class sessions is called SCM and was written by Aubrey Jaffer (jaffer@ai.mit.edu).
On MathLAN, it's usual to run SCM in the hpterm terminal emulator. Click
on the icon of a monitor-and-keyboard on the bottom row of the HP VUE front
panel to create an hpterm window. To run SCM in interactive mode, move the
mouse pointer into the window and type scm -p1
at the prompt.
(The -p1
option suppresses a running commentary that SCM
otherwise provides, telling you how much time and memory it uses to perform
each of the operations.) SCM will signal that it is ready to begin
processing Scheme definitions and expressions by printing its own prompt,
which is a greater-than sign followed by a space. At this point, the
contents of the window will look something like this:
bourbaki% scm -p1 >You type in a definition or an expression after the prompt. You may use more that one line if necessary; SCM will not react until you have typed a complete Scheme definition or expression, no matter how many lines it requires. At the end of the definition or expression, press the Return key to terminate the line. SCM will then display the value of the expression (or the symbol
#<unspecified>
in the case of a
definition or an expression that is evaluated for its side effect) and
print its prompt again, thus:
bourbaki% scm -p1 > (+ 28 39) 67 >To exit from SCM, press Control/D at the prompt. A second Control/D will close the window.
To run SCM in batch mode, add the name of the file containing your Scheme
program to the command line, followed finally by the option
-b
. (It is important that the -b
be placed at
the end.)
bourbaki% scm -p1 foo.scm -b bourbaki%In batch mode, neither prompts nor the results of evaluating expressions are printed; any output that is to appear must be generated by the Scheme program itself, using such output procedures as
display
and
newline
.