[Swift-devel] Coding a server in Swift

[Ben Clifford]

That's a fairly crazy thing to do, I think. Here is a digression which may 
or may not be relevant at the end.

In the past I thought a bit about handling "ever growing" data sets (for 
example, a new dated file of sensor readings is placed in an input 
directory every hour or day or week), with Swift causing some processing 
to happen on each of those files as they appear.

In the case of a fixed-size dataset, that's fairly straightforward: map 
all the files in a directory into an array, and then use foreach to run 
something on all of those files, generating corresponding output files.

At the high level, Swift shouldn't have a problem with a directory that 
grows: you map a directory that is still growing, and you run a foreach 
over it.

Most of swift can handle an array that is not yet complete - thats core to 
the parallel behaviour.

However the present mapping infrastructure can't deal with that (was my 
opinion at the time). It might be possible to implement a Java-land 
function that instead creates the appropriate array object over time 
rather than through mapping with a mapper. I'm not sure. Then, call that 
"polldir" and you could saysomething like:

  a = polldir("/path/to/dir")
  foreach e in a  {
    ...
  }

I think the behaviour you desire is then fairly straightforwardly 
expressed.

It might be interesting for someone to have a deeper investigation into 
whether something like polldir could be easily implemented (although in 
the future, mappers would be the right place, I think)

-- 
http://www.hawaga.org.uk/ben/