Could you elucidate?
The biggest problem I see with people dealing with Tcl is that they carry their understanding that {} delineates scope (or something else lexically). Of course, this is wildly untrue in Tcl as {} is simply a "quote" operator.
This stuffs people up horribly until they unlearn the idea that {} has semantic meaning.
puts Hello!
puts "Hello!"
puts {Hello!}
# or even
{puts} {Hello!}
# x is not actually a list, but may appear that way if a and b are nice
set x "$a $b"
# Proper way:
set x [list $a $b]