Tcl, in its own way, is more powerful than both Ruby and Python in that only the syntax is a given. There is nothing special about 'if', 'while', and other control structures, which are not syntax, but commands. Indeed, you can write your own control structure commands in Tcl itself, with 'do ... while' being a classic example.
Can you elaborate on why you think Python's lambda is castrated?
Python's lambda doesn't allow the use of statements (correct me if I'm wrong I haven't written Python in a few years and they may have "fixed" this).
Meanwhile Ruby only allows expressions too - the catch here is that everything in Ruby is an expression.
That is why people consider them castrated - in most languages I'm aware of that have a "lambda" statement, it can be read as "create an anonymous function that executes this body of statements". In python it reads as "perform a simple transformation or calculation on or with these arguments", as that's all it's generally good for.