RE : Functions may leak information about names(!) oflocalvariables.




> 
> The problem you have encountered is that t is a synonym for the truth value
> true.
> 

I don't think that it is the problem. See:

g(s):=block([u],local(u), u[4]:subvar(s,4), u[4]);

now g(u) => u_4
and g(t) => 64

In my point of view the problem here is that we have a conflict with global
 and local variable name.

And local variable override global variable in function body as in any programming language
that I know.

Laurent.