[Haskell-cafe] How to use STArray?

[Alistair Bayley]

> > makeArray :: Int -> Int -> a -> ST s (STArray s Int a)
> > makeArray lower upper val = newArray (-lower, upper) val
>                                         ^
> Is negation of lower intentional here?

Yes, 'tis. Arguable as to whether or not it's a good idea, as it
changes the inerface. In my program I use two types of array:
 - indexed from 1 to n
 - indexed from a -ve lower to a +ve upper

So in this case it made sense to just pass the lower bound and negate
it in the wrapper.