I also suspect I’ll be doing a [...]]]> So I decided to pick up the Scala language. Having done Ruby for a couple of years now Scala is one of the few, if not the only language that’s gotten me excited. Being a first class citizen on the JVM has many advantages and I’m really liking LiftWeb.

I also suspect I’ll be doing a bit more Java related stuff in the very near future (stay tuned for that one ) so it’s a good idea to dive into the J world again, and what better way then with Scala!

Problem definition: there is an issue with some XML files which came with a large batch ingest for one of our clients. In short there are a bunch of track elements in the XML which each element having a on_disc and sequence_number (think audio CDs) . However, the sequence_numbers should always be incremented e.g. if you have 2 tracks on disc 1 and 3 tracks on disc 2 the tracks on disc 2 should be have sequence numbers 3,4 and 5 respectively. The XML files we got have reset the sequence_number to 1 whenever a new disc begins.The fix is thus a simple matter of adding the highest sequence number of the previous disc to the sequence number of the current disc. Easy enough.

I tried to implement this in Scala and one of the helper methods calculates the highest sequence number of a given disc. This is the odd part though

// The XML is first parsed to read all tracks
// These are stored in a tuple list
// Note the order of the tuples!
// Tuple values are (on_volume, sequence_number)

val sequence = List((1,2),(1,1),(2,1),(2,2),(2,3))

// Find the max value given a volume
def maxVal(vol: Int): Int = {
  var max = 1
  for (t <- sequence
    if t._1 == vol;
    if t._2 > max) max = t._2
 max
}

println(maxVal(1))

Now my Ruby brain would expect this to print out 2, however when you run this code the result will be 1! That’s because the filters are actually creating a new list before feeding that to for clause so max is always 1 in the test. I did not expect this

The solution is quite simply. Just make sure pg_config can be [...]]]> I need to fix a project which uses PostgreSQL. On a fresh Leopard install with postgresql 8.3 installed from ports I ran into this problem:

$ sudo gem install pg
Building native extensions.  This could take a while...
ERROR:  Error installing ruby-pg:
ERROR: Failed to build gem native extension.

The solution is quite simply. Just make sure pg_config can be found by the gem installer.

$ mdfind pg_config|grep bin|uniq
/opt/local/lib/postgresql83/bin/pg_config

In this case make sure /opt/local/lib/postgresql/bin is available in the path when executing the gem command

$ PATH=/opt/local/lib/postgresql83/bin:$PATH sudo gem install pg

Update: and back again (2009-03-06)

We sold our apartment a few weeks before the credit crunch hit hard, phew! We already purchased a new house (new construction) last year. Last week we had to move out of apartment. Unfortunately the new house is not yet finished. Well it is, but the utility companies still need to their stuff and the [...]]]>

We sold our apartment a few weeks before the credit crunch hit hard, phew! We already purchased a new house (new construction) last year. Last week we had to move out of apartment. Unfortunately the new house is not yet finished. Well it is, but the utility companies still need to their stuff and the municipality needs to finish the roads, in that order. the new location is just 1 block away because we really like Osdorp and wanted to stay in or around Amsterdam.

In the meantime we’ll be moving between my sis and brother-in-law. c’mon waternet, move!