e of a hash
function usually depends on more than just the type of the data you want
to hash. For example, there are lots of hash functions over Int, but
you'll want to pick one that works well for the distribution of values
you have.
There really ought to be
Many thanks for Data.HashTable, which I am about to use. Unfortunately
I seem to need an unseemly hack because the key I want, namely ThreadId's,
don't have a hash function defined, and defining one requires me to muck
around with GHC internal functions. Could some more hash fu
