Compiler Versions

[George Russell]

Simon Marlow wrote (initially quoting me, snipped):
>> What one
>>wants to know is whether
>>(1) version X was released later than some given date;
>>(2) version X is lexicographically subsequent to [sequence of 
>>integers]
...
> I'm not convinced of the need to have a date attached to all versions,
> though.  Under what circumstances do you imagine needing (1) above,
> where (2) won't do?

In an ideal world dates wouldn't matter, but in the real world programs
bitrot, and a bundle of source code which works with version N of a
compiler may very well not work with version N+1.  Clock times are useful
here because they do not depend on the project.  They also cost virtually
nothing, since it's easy to put them in automatically when Version values
are generated.

I've no objection though to having the relevant field in the Version type
Maybe ClockTime rather than ClockTime, in which case operation (1) should
give an error.  On the other hand you could just set the ClockTime value
to (error "Sorry, I can't be bothered to figure out the release date")
as a way of dealing with historical releases and getting the same effect.
But I really think it should at least be possible, indeed the default,
for Versions to contain a timestamp.