MJ - After watching Christian Gollwitzer and dkf's talks on EuroTcl I was contemplating an idea for Tcl9. A big reason of Tcl's flexibility is brought by EIAS, however this is a double edged sword.
So how about a Typed Tcl where you can define and use Tcl_Objs with a specific internal representation and conversion functions to other intreps without passing to string.
You would need to declare the value as a typed value and as soon as you play the EIAS card, you will get an error unless you make the shimmer explicit.
This has a couple of benefits.
This approach is complementary to the approach of speeding up Tcl by code analysis. Sometimes I will just know when I don't need EIAS but I will just need speed instead.