[Ur] Proposing 'readTime'

[Gian Perrone]

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Hi all,

I've come upon a need to deal with some time functionality, and the
current pair of functions timef/readUtc appear insufficient --
principally, because there exists no easy way to detect the current
timezone so as to manually perform the timezone adjustment to UTC.
Consequently, the following does not work:

[...]
    currentTm <- now;
    fmt <- return (timef "%x %T" currentTm);
    error (case readUtc fmt of None => <xml/> | Some t => <xml>{[fmt]} -
{[t]}</xml>)

We should expect this to print the current time twice, however, if your
local time happens to not be in UTC, then you're going to get a timezone
adjustment, and two completely different times displayed!

I propose a 'readTime' function to exist in addition to 'readUtc' that
will simply read a formatted time string as though it were in local
time.  I've attached a patch to implement just this when applied against
the latest Ur/Web from Mercurial.  In my example above, replacing
'readUtc' with 'readTime' provides the expected behaviour, such that
readTime is properly an inverse of timef.

Thanks,
Gian
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