[plt-scheme] Time Base

From: John Clements (clements at brinckerhoff.org)
Date: Tue Dec 15 17:24:12 EST 2009

On Dec 15, 2009, at 1:20 PM, Doug Williams wrote:

> The data/time routines in PLT Scheme have many warning about using the actual values for current-seconds, etc directly and about the base time that is used. At least on Windows and Linux (Ubuntu 9.10 in this case), current-inexact-milliseconds seems to return the number of milliseconds since  00:00:00.000 1 Jan 1970. Is this the case for all systems.
> I am implementing RFC 4122 (UUIDs) and need a good time implementation. I was using SRFI 19, but it turns out to be problematic. The reference implementation, which is pretty much what is in PLT Scheme, has errors - in particular, the nanoseconds calculations are off by a factor of 100 and it ripples through some of the other calculations and the author has withdrawn support. There are patches around for some of these problem in other Scheme implementations, but I haven't tracked them all down (or checked the PLT Scheme bug list). And, I really don't need all that SRFI 19 provides.

Just between us, the SRFI-19 implementation is dreadful.  Don't tell anyone I said that.  Especially not anyone else on the plt-scheme mailing list.

More seriously: it sounds like you're in a position to contribute a couple of (failing) test cases.  Even though you're not going to be using the library, others could potentially benefit from your knowledge, if you're willing to share.

Many thanks,

John Clements

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