Software

This evening, I released HDBC 1.0.0.

HDBC is a database API for Haskell. I wrote it after being unsatisfied with HSQL. HDBC at a certain level feels similar to Perl's DBI. But it is both simpler and more powerful, IMHO, thanks in large measure to Haskell language features.

The HDBC homepage is here.

Users of Debian's testing or unstable distributions may be noticing messages from apt saying things like:

WARNING: The following packages cannot be authenticated!

  foo bar baz

Install these packages without verification [y/N]?

I noticed today that google doesn't turn up good hits for the fix. The fix is really simple:

apt-get install debian-archive-keyring

apt-get update

That's it. You now have secure packages from Debian. Nice, eh?

I finally purchased my first iPod: a black 60GB iPod video model. I had been holding off for years. The iPod sounded nifty, but I just didn't quite go there.

The thing that finally won me over was the camera connector. It lets you plug your iPod directly in to a digital camera. The iPod can download photos from the camera to its internal disk without the need for a PC. Very slick.

So anyway, we got the iPod and the camera adapter at the Apple store in Cambridge -- a quick subway ride from Usenix. They were out of stock on the FM tuner, so I ordered that online.

The next step was to get the iPod working with Linux. I currently have it working with both music and video. Here's how I did it.
Continue reading "An iPod under Linux"

At work, we've been using vserver for virtualization for some years now. Due to various reasons, we're looking at Xen.

I've been trying to switch my workstation to use Xen. I've enountered a few issues so far. Probably these will go away as I learn the system.

Overall, my greatest gripe is the documentation. It is outdated and just plain wrong far too often. For instance, there's a place where it says to run "make ARCH=xen xconfig", but the Xen kernel patches don't (any more, at least) provide a xen arch.

The next gripe is the very weird kernel build system. Xen doesn't ship a diff against a kernel tree. They instead ship whole files to extract atop a particular kernel version. Annoying and unwieldy. There is a command to generate a diff, but you have to download the full kernel tree first.

A couple of other gripes: There is little documentation on memory management (can Xen adjust the RAM usage of running VMs?), on 64-bit systems (can you run a 32-bit kernel under a 64-bit hypervisor? how about a 64-bit kernel that supports 32-bit userspace?)

I'm also having trouble with my forcedeth card locking up under Xen.

However, I've heard of lots of people having good luck with it so I'm going to keep trying.

But one would think that basic docs could be actually worked on a bit more.

Following the "release early, release often" motto, I am happy to announce version 0.1.0 of HSH, the Haskell shell.

You may obtain it with:

darcs get --tag 0.1.0 http://darcs.complete.org/hsh

Things are still very rough in many ways, but this version already lets you:

• Run commands
• Pipe things between commands
• Pipe command input/output into and out of pure Haskell functions
• Pure Haskell functions are as much a first-class citizen as is grep or cat

Here is an example session: (some lines wrapped for readability)

$ ghci -fglasgow-exts HSH

*HSH> run $ ("ls", ["."])
COPYING    HSH        HSH.hs    TODO    announcements  testsrc
COPYRIGHT  HSH.cabal  Makefile  _darcs  test.hs

*HSH> run $ ("ls", ["-l"]) -|- ("wc", ["-l"])
12

*HSH> :m +Text.Printf
*HSH Text.Printf> let countLines = (zipWith (\i line -> printf "%-5d %s" i line) 
       [(1::Int)..])::([String] -> [String])

*HSH Text.Printf> run $ ("ls", ["-l"]) -|- countLines -|- ("grep", ["hs$"])
6     -rw-r--r-- 1 jgoerzen jgoerzen  1285 Jun  6 09:43 HSH.hs
11    -rw-r--r-- 1 jgoerzen jgoerzen   565 Jun  6 09:43 test.hs

*HSH Text.Printf> :m +Data.List
*HSH Text.Printf Data.List> run $ ("ls", ["-l"]) -|- countLines -|- 
         filter (isSuffixOf "hs")
6     -rw-r--r-- 1 jgoerzen jgoerzen  1285 Jun  6 09:43 HSH.hs
11    -rw-r--r-- 1 jgoerzen jgoerzen   565 Jun  6 09:43 test.hs

*HSH Text.Printf Data.List> run $ ("ls", ["-l"]) -|- countLines -|- filter (isSuffixOf "hs") 
       -|- ("tr", ["a-z", "A-Z"])
6     -RW-R--R-- 1 JGOERZEN JGOERZEN  1285 JUN  6 09:43 HSH.HS
11    -RW-R--R-- 1 JGOERZEN JGOERZEN   565 JUN  6 09:43 TEST.HS

*HSH Text.Printf Data.List> let generator = \(_::String) -> unlines . map show $ [1..20]
*HSH Text.Printf Data.List> generator ""
"1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n11\n12\n13\n14\n15\n16\n17\n18\n19\n20\n"
*HSH Text.Printf Data.List> run $ generator -|- ("grep", ["1"])
1
10
11
12
13
14
15
16
17
18
19

Future versions will likely simplify syntax to make it easier to write scripts and introduce a sh to hsh converter. I also plan to add pure Haskell tools for some common shell-ish things that one could do in Haskell.