🚀 go-pugleaf

In article <OLSON.91May3124040@lear.juliet.ll.mit.edu> olson@juliet.ll.mit.edu ( Steve Olson) writes:

|In article <STEPHEN.91May3051250@estragon.uchicago.edu> stephen@estragon.uchicago.edu (Stephen P Spackman) writes:
|   I have to disagree. A good machine language (one with no Catch Fire &
|   Burn instructions) for a machine without programmer-visible caching is
|   both strongly and statically typed, simply by virtue of the fact that
|   all consequences of a given machine state are defined. You are making
|   the mistake of imagining that addresses and ints and so forth exist in
|   object code; but they don't. Those are abstractions in your mind.
|   Ultimately they are NOT represented in the machine model. Bits go
|   here, bits go there, the memory holds bits and nothing else. The
|   (only) data type is the bit....
|
|If one puts an integer into a floating point instruction, one might
|get a deteriminstic result. But so what?  The result wouldn't be
|meaningful.  I might as well argue the only real data type is the
|voltage level.  

I don't believe so, because the machine language is defined in terms
of bits and not voltages. If we were looking at hardware bus
behaviours at 100MHz or more, I'd agree with you.

|   I'm really not trying to be silly here. The fact that machines are
|   strongly typed underlyingly is the thing that makes secure
|   implementations possible. If something could happen to be in memory
|   that wasn't a bit, no language layered above could ever have
|   guaranteed behaviour... (which is why it's bad when the hardware fails
|   - untrapped type violations then CAN occur.... :-).
|
|According to your definitions a weakly typed language is impossible on
|deterministic hardware.  Depending on how you set up your starting 
|definitions, there might be some narrow, literal truth to it, but it
|dosen't seem like a terribly useful way to think about programming languages.

Oh, no! What the language does NOT define is of the essence. Each
impemetation is in some sense underlyingly typed, but that doesn't
reflect on the language at all. Compilers will be specified in terms
of language semantics, not machine code translations....

But I will admit to the philosophical stance that "untyped" data do
not exist - it may be convenient to pretend otherwise, but ultimately
the only reason a function should not validate its arguments is if it
is intended to process non-data - if it's a GIGO engine. And I just
don't see how this can possibly be relevant to any human endeavour.
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stephen p spackman         Center for Information and Language Studies
systems analyst                                  University of Chicago
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