Re: Do we really need virtual machines?

Nicola Musatti wrote:


> According to their proponents virtual machines such as JVM and CLR
> are the solution to all our (programming) problems, of which
> portability is but one.


You are right. Distinct instruction sets are an obstacle to
portability. But my experience with learning Java tells me another
lesson: The instruction is hard enough to create portably (see below)
but it is only the first step of portability. Look at Java and C#: The
most important obstacle in portability is the amount of libraries with
all their quirks and dead ends (AWT).


Has anyone ever noticed that the "standard libraries" that come with
Java and C# are attempts to recreate Unix-like Operating Systems ?
Including APIs for memory, file system, scheduler, terminal, printer,
network, clock, GUI ... O'Reilly publishes dozens of Java books. What
are they all about ? Library details; most of them becoming obsolete
if C# succeeds. Stuffing Java library details into my brain seems like
a waste of brain capacity.


> Now, this being the compiler forum, I'm interested in learning about
> the advantages of virtual machines from the compiler writer
> perspective.


Our moderator (John) has pointed out _very_ often that language
designers should first learn the lessons of the UNCOL period (1960s)
before they start inventing yet another UNCOL-variant. Nobody listens
to John; they are just too busy.
[The original UNCOL proposal was published in the CACM in 1958, and
the report on the first (and last) version was in the 1961 winter JCC
proceeedings. Also see a collection of UNCOL references I pulled
together in comp.compilers 13 years ago at
http://compilers.iecc.com/comparch/article/91-12-058 -John]

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