> Yes, every time I write df[df.sth = val], a tiny part of me dies.

That's because it's a bad way to use Pandas, even though it is the most popular and often times recommended way. But the thing is, you can just write "safe" immutable Pandas code with method chaining and lambda expressions, resulting in very Polars-like code. For example:

  df = (
    pd
    .read_csv("./file.csv")
    .rename(columns={"value":"x"})
    .assign(y=lambda d: d["x"] * 2)
    .loc[lambda d: d["y"] > 0.5]
  )

Column-level name checking would be awesome, but unfortunately no python library supports that, and it will likely never be possible unless some big changes are made in the Python type hint system.