A python "lambda expression" can effectively only be a one-liner - basically the return line of a function minus "return".

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.

I think it is due to the statement/expression dichotomy that Python exhibits.

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.

A lambda is traditionally a functional programming product--think Lambda Calculus. Functional programming doesn't have statements, and neither should lambdas. Or do you mean anonymous function, in which case you're right.

They don't plan to fix this, it's part of the core philosophy