Arrays and arrays

[Simon Marlow]

> Since you're on the line, could you confirm or deny that the (//)
> operator is something equivalent to (roughly):
>=20
>     a // ps =3D runST (thaw a >>=3D \u -> update ps >> unsafeFreeze u)
>=20
> I.e. that the list of updates are treated as an atomic operation?
> Because doing it that way explicitly sure didn't seem to help.

Yes, it is.

> OTOH, doing lots of small (//) seems to be faster than doing a few
> large ones (containing the same updates).  Go figure.

That's bizarre.  Perhaps the results are obscured by some other
optimisations which are happening.

Cheers,
	Simon