(*
* methodless-primes.cl
*
* Designed by Jesse H. Willett, jhw@cory, 11103234, with
* Istvan Siposs, isiposs@cory, 12342921.
*
* This program generates primes in order without using any methods.
* Actually, it does use three methods: those of IO to print out each prime, and
* abort() to halt the program. These methods are incidental, however,
* to the information-processing functionality of the program. We
* could regard the attribute 'out's sequential values as our output,
* and the string "halt" as our terminate signal.
*
* Naturally, using Cool this way is a real waste, basically reducing it
* to assembly without the benefit of compilation.
*
* There could even be a subroutine-like construction, in that different
* code could be in the assign fields of attributes of other classes,
* and it could be executed by calling 'new Sub', but no parameters
* could be passed to the subroutine, and it could only return itself.
* but returning itself would be useless since we couldn't call methods
* and the only operators we have are for Int and Bool, which do nothing
* interesting when we initialize them!
*)
class Main inherits IO {
main() : Int { -- main() is an atrophied method so we can parse.
0
};
out : Int <- -- out is our 'output'. It's values are the primes.
{
out_string("2 is trivially prime.\n");
2;
};
testee : Int <- out; -- testee is a number to be tested for primeness.
divisor : Int; -- divisor is a number which may factor testee.
stop : Int <- 500; -- stop is an arbitrary value limiting testee.
m : Object <- -- m supplants the main method.
while true loop
{
testee <- testee + 1;
divisor <- 2;
while
if testee < divisor * divisor
then false -- can stop if divisor > sqrt(testee).
else if testee - divisor*(testee/divisor) = 0
then false -- can stop if divisor divides testee.
else true
fi fi
loop
divisor <- divisor + 1
pool;
if testee < divisor * divisor -- which reason did we stop for?
then -- testee has no factors less than sqrt(testee).
{
out <- testee; -- we could think of out itself as the output.
out_int(out);
out_string(" is prime.\n");
}
else -- the loop halted on testee/divisor = 0, testee isn't prime.
0 -- testee isn't prime, do nothing.
fi;
if stop <= testee then
"halt".abort() -- we could think of "halt" as SIGTERM.
else
"continue"
fi;
}
pool;
}; (* end of Main *)