Thu Aug 2 14:09:32 EDT 2018

arrays, ST

I want fast mutable arrays.
ST vs IO, and the 'U' unboxed version.

First, what is ST?


Basically, IO for "inner loops".


EDIT: This is quite cool.  I ran into this before, but could not quite
appreciate the importance.  This means there is as good as no reason
to go out of Haskell, besides platform size (i.e. Haskell is big).

Not simple though.  Rank-2 types.

I get the basic idea, but do not see exactly how to make sure that two
instances of s are the same.