[plt-scheme] PLT4 expectations

Matthew Flatt writes:
 > At Mon, 10 Mar 2008 14:34:49 +0000, "Paulo J. Matos" wrote:
 > > The idea of PLT4 creating by default immutable pairs and the so, means
 > > that it also opens the possibility for far more and better
 > > optimizations in the compiler, right?
 > 
 > I doubt that there are many new optimization opportunities that matter
 > in practice.

Well, you could make "list?" be O(1) instead of O(n), at a cost of one
bit per cons cell.  Or is that cost too high?  I don't really know if
there are any spare bits available.

--dougorleans at gmail.com