To make sure that filehandles are closed properly I've lately written
> with_file functions that take a filename and a function.
> It then opens the file, invokes the function (in a try block), and closes
> the file (even if the try block threw an exception).
> That way no file handles leak, and the GC is not needed to clean up.
>
> This is in some ways similar to RAII in C++ where destructors
> automatically clean up resources when you leave a scope.
> Maybe there should be a small library that provides these convenience
> functions (other resources can be handled similarly,
> opendir/closedir comes to mind, but there are probably other cases where
> an explicit close-like functionality is needed).
>

Those functions are defined in Batteries, see BatPervasives.with_dispose (
http://ocaml-batteries-team.github.com/batteries-included/hdoc/BatPervasives.html),
BatFile.with_file_in and BatFile.with_file_out (
http://ocaml-batteries-team.github.com/batteries-included/hdoc/BatFile.html
).

They are indeed very useful !
Cheers,
ph.