In order to be able to display computational results to the
screen it is necessary to introduce a few primitives into A++.
It will also be very helpful to introduce symbolic constants
and strings into A++.
These extension are briefly described below:
vmzero a reference to the number ``0'' in the machine.
vmtrue a reference to the boolean value 'true'
in the interpreter.
vmfalse a reference to the boolean value 'false'
in the interpreter.
double-quoted-string This abstraction introduces
strings into A++. They are needed in the context of the ``load'' primitive
allowing to load A++ - code from a file.
single-quoted-string This abstraction introduces
symbolic constants into A++. They are convenient in the context of
object oriented programming, when sending messages to objects..
incr This primitive is used to increment a number in the
virtual machine by one.
print This primitive displays a number or a boolean value
on the screen.
load Primitive
allowing to load A++ - code from a file.
equalx Primitive allowing to compare data items other than
Church Numerals (numbers directly derived from ARS).
quit Function to terminate execution of program.
These primitive abstractions are used in the following
A++ - lambda abstractions
verwendet:
