gc.spl

Int _bssSize() {}
Int _bss(Int pos) {}
Int _stackSize() {}
Int _stack(Int pos) {}

Void _touch(t obj) {}
Bool _valid(Int val) {}
(Int,Int) _read(Int addr) {}

Int _reinitHeap() {}
Void _mkAvail(Int pos) {}
Bool _reached(Int pos) {}

Void gc_mark(Int addr)
{
    while(_valid(addr)) {
	(Int,Int) cell = _read(addr);
	_touch(cell);
	gc_mark(fst(cell));
	addr = snd(cell);
    }
}

Void gc_sweep()
{
    Int i = _reinitHeap();
    while(i > 0) {
	i = i-1;
	if(!_reached(i)) _mkAvail(i);
    }
}

Void gc_collect()
{
    Int i = _stackSize();
    while(i > 0) {
	i = i - 1;
	gc_mark(_stack(i));
    }
    i = _bssSize();
    while(i > 0) {
	i = i - 1;
	gc_mark(_bss(i));
    }
    gc_sweep();
}

Void doNothing(u x) 
{
    return;
}

Void main()
{
    Int i = 0;
    while(True) {
	doNothing(1:2:3:4:[]);
	print(i);
	i=i+1;
	if(i%500==0) gc_collect();
    }
}