[M3devel] what to do about file sizes being 32bits?

[Tony Hosking]

Agreed.

On 7 Jan 2010, at 20:37, Rodney M. Bates wrote:

> 
> 
> Tony Hosking wrote:
>> On 7 Jan 2010, at 06:22, Jay K wrote:
>>> I'm working on this..
>>> Attached is what I have so far.
>>> Posix needs work.
>>> Most code continues to not work for files >4GB on 32bit, but it is a start.
>>> It seems to me I shouldn't have o use VAL(i, LONGINT) to convert an INTEGER to a LONGINT, as all INTEGER values fit.
>>> Similarly I should be able to compare a LONGINT to 0 directly, instead of 0L.
>> Again, I discourage this as not in the spirit of the Modula-3 type system which abhors implicit casts.
> Indeed, Modula-3 has no implicit casts at all.  But it does have something
> that sometimes accomplishes the same result in a way that is far simpler
> to define and represents a higher level of abstraction, namely, the
> concept of assignability.  A value, e.g. 10, can be in the value set of
> many types (INTEGER, many of its subranges, and now LONGINT and many if
> its subranges too).  If so, it can in certain carefully specified cases,
> be assigned from one of these types to another, without any syntactically
> explicit notation required of the programmer.
> 
> This represents the more abstract view that 10 is 10, as opposed to the
> usual view that 10 sitting in a byte is not the same as 10 in a word.
> Of course, at the machine level. they are not the same, but in Modula-3,
> that is only a representation matter that the compiler must take care of,
> not a high-level language matter that needs pages of rules to define.
> 
> It took me years to fully understand the implications of replacing implicit
> type conversions by the assignability concept, but I now consider it one
> of Modula-3's great ideas, even if it is a small thing.

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