Incoherent mumblings
Archive for September 2008
I thought I’d start posting little notes about papers I read, especially if I find them interesting and worth reading. So here we go!
I read this paper on the bus this morning. I suspect I got it off Lambda the Ultimate a while back, printed it and then kept it in my bag for several months.
A friend pointed me to this film about what money is. I’ve known since high school how banks create money, but I’ve never thought it through to its logical, and somewhat worrying, conclusion. Well worth watching I thought.
I’ve found myself getting confused over the Data.Time modules a few times now. Today I wanted to do something that I ought to be simple both to do (it was) and find out how to do (it wasn’t, at least not for me). I thought I’d write it down, because I’m bound to forget about it otherwise, and it might be helpful for some other poor soul out there.
I wanted to store a date in a database (SQLite) using Haskell (HDBC). Since I’m only interested in the date and not the time I chose to represent it in Haskell as a Date.Time.Calendar.Day. For Day 0 means 1858-11-17. HDBC on the other hand needs the date in seconds since epoch (1970-01-01 00:00 UTC), which conveniently can be represented with a single Integer. Time.Data.Clock.POSIX contains a few handy functions to convert between POSIXTime (NominalDiffTime) and UTCTime. However, there are no special functions for converting between an Integer and NominalDiffTime. The way I found was to do it via the class types that NominalDiffTime implements.
First I thought that Enum might offer the solution, but my experiments with that was a bit confusing:
> pt <- getPOSIXTime 1221603766.526661s > fromEnum pt 4118657661830593344 > toEnum 4118657661830593344 :: POSIXTime 4118657.661830593344s
Not really the result I had hoped for. No, instead the function to use to get the Integer is floor, and the only way I found to convert a NominalDiffTime from an Integer is to go via a Ratio:
> fromRational (1221603766 % 1) :: POSIXTime 1221603766s
Have I missed something or is this the best way to achieve this?
I’d love to see the Gmail S/MIME plugin for Firefox gain support for PGP/MIME. I can’t imagine it’d be too hard to add for someone who’s familiar with JavaScript and Firefox plugins. Or maybe there’s some other plugin out there that offers PGP/MIME support in Gmail?
Oh, and no, FireGPG isn’t good enough, it doesn’t do PGP/MIME, it doesn’t automatically verify/decrypt received emails, and it requires too much mouse interaction!
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