[Haskell-cafe] Fwd: Data.Time

sent from wrong account - message follows:

I've found most of the time library to be quite useful, but the parsing to be worthless (I've tried to get someone to prove me wrong already, and would be happy if someone could on this thread!).

Specifically, the formatTime function, if it ever strips out padding (by zeros or spaces), results in a time that is unparseable. The fact that formatTime and parseTime are not capable of being inverses of each other seems like a major flaw, when you think that this is not a parseable date:

2011/1/30 (because the month must be padded by zeros).

Even though it is very easy to print, and occurs commonly in the world.

Because of this, I use formatTime to write my times, and then have a custom parser to parse them back out. Which makes me think that this is a broken library

On Jun 27, 2011, at 10:37 AM, wrote:

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On Mon, 27 Jun 2011 11:15:28 +0300 Yitzchak Gale wrote:

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The biggest shortcoming, in my opinion, is that the documentation assumes that the reader is very familiar with the Haskell type system, and with viewing type signatures and instance lists as an integral and central part of the documentation.

In particular, Haskell's standard numeric type classes and the conversion functions between them play a central role in the API of Data.Time. But you wouldn't realize that unless you have read the type signatures and instance lists in the Haddocks very carefully, and have thought about it for a while.

This is exactly right.

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Another problem, as Malcolm pointed out, is that because of the sheer size of the library, a quick-start guide for the common cases would be extremely helpful for newcomers.

That would be very, very helpful. I had a few working examples things were much better. Finding a starting place, any starting place, proved to be quite elusive. Also the fact that asking for the current time traps you in IO hell, doesn't help, although it's clear that it should be that way.

Brian

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