Blair,

The ARM library I was working on actually has the ability to return an Either[List[Throwable],T].   This lets you decide what to do with your exceptions.

Also ->

map and flatMap are assumed to be lazily executed (i.e. you can't acquire/release the resource if you're modifying it)
foreach is assumed to be eagerly executed (you almost have to do this... otherwise when will you run it?)


The final fun was if you pass a function f of Resouce => ? <: Traverable[T], we made the assumption that it would be safe to return a "managed" Traversable.   The returned traversable will open the resource, call the mapping function, call foreach on the internal traversable, and then close the resource when done.   This was my first attempt to see if I could use the type system to determine when it is safe to extract from a monad.  This is the piece that's strange...

basically I wanted this to work:

val lines = for { file <- managed(new java.io.File("some.txt"))
       stream <- new java.io.FileInputStream(file)
       line <- makeLineIterator(stream) } yield line

Which... does in fact work as I wanted it to... at times.   Anyway, I'm still fighting with whether or not the auto-leak feature is useful.  If not, the library can be greatly simplified.

Also... one thing I was using this for was RMI/JNDI.   In that case I wanted to create a managed resource in a configurable manner...  i.e. one that would 'retry" the remote method on failure after some specified timeout.  This also required some threading magic and contexts.   I'll try to get the code open-source to see if it's of any use to others.

- Josh