Re: Java equivalent of C++ Spirit or Boost Graph Library ?

Jeffrey Schwab wrote:


I'm not sure that I'd call it "excellent", but however you judge it, it is not
at all suitable for the OP's purposes. He will need proper garbage collection,
so it's a choice between using a system-supplied one, or writing your own /in/
C++.

But a word of warning: GC algorithms/implementation tend (naturally) to be
tuned to the allocation patterns of the languages for which they are intended.
The pattern of references between objects in Java may be very different from
those naturally arising in a functional language implementation -- and it might
also depend on the style of the implementation. (I remember a paper comparing
the Boehm conservative collector for C/C++ in an implementation of Lisp and a
combinator-machine implementation of some FP language -- it didn't work well at
all for the latter application, probably because the reference networks were
much bigger and more tangled).

In this case, I'd be a bit wary in case the JVM's collector assumed that chains
of object references were short enough to be followed by explicitly recursive
function calls. If so, then there /may/ be a risk that it would run out of
stack space trying to GC an object-network that arose from some styles of FP
implementation. It's easy enough to test -- just create a long chain of
objects (longer than would naturally arise in the FP language implementation)
and see if the collector breaks ;-)

    class Cell { Cell next; }

    Cell head = new Cell();
    Cell tail = head;
    for (long i = 0; i < LONGEST_PLAUSIBLE_CHAIN; i++)
    {
        tail.next = new Cell();
        tail = tail.next;
    }

    head = tail = null;

    // now wait until the GC has had a chance to crash...

Please note that I'm not saying that the GC in any particular JVM /would/ be
unsuitable for an FP language implementation, only that there /might/ be an
issue (depending on many factors, including the implementation strategy of the
FP language itself).

    -- chris