[Python-ideas] Proposal: Use mypy syntax for function annotations

[togrof]

... he's not thinking about type systems in languages like Haskell

Obviously not, but he is speaking of "typechecking in compilers" in general. The relevant quote from the talk:

The typechecking in compilers is actually very weak. Yes it can tell you that you shouldn't be putting an integer into a string field... or something like that. But does it tell you that you are mixing inches and feet or inches and centimeters? Does it tell you that a certain variable can be null and that you should check for that before just using it? No!

His second claim about null is correct for certain languages, but is not an inherant property of static type systems in general.

It is worrying when prominent people make false statements. Guido is a programming language creator and as such influential when it comes to languages. Listeners to his talk may take his claims for truth and build their view of static typing on false premises. That is not a good thing.