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0 pointsHotHotLava5y ago0 comments

I mean, how would you possibly know about the type bugs that you didn't catch? I once ported a medium-size (ca. 5k LoC) python library to native C++, and we discovered a ton of latent type bugs that had stayed unnoticed in the code base for almost a decade. Things can randomly work for a long time due to duck typing, and then break in unpredictable ways.

Over time, this has a very noticable impact on development speed, and in a very painful way for the individual developers who need to spending your time tracing the various call paths in unrelated code and build up a mental model of the involved types every time they want to do a nontrivial change, and then deal with the fallout of unintentional bugs due to missed code paths for an unpredictable amount of time as they are discovered.

So when there is a solution that can completely eliminate this class of bugs in an automated way, this sounds like a very appealing feature.

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4 comments · 2 top-level

IgorPartola5y ago· 2 in thread

I know because monitoring tools tell me when bugs occur, because exceptions are thrown. And I know because the code doesn’t run if you pass on a dict instead of an int. Statically typed languages have type systems that are by necessity strict but in a language like Python you don’t need to worry about whether your variable is a uint8_t or a uint16_t unless you specifically care about that. And more complex bugs like passing a list with the wrong number of members is not going to be caught by the type checker.

HotHotLavaOP5y ago

Once a bug starts causing exceptions, it's no longer undetected. Then it becomes part of the post-deployment "fallout".

Too5y ago

You still need to worry whether an user_id-argument is int, str or maybe even uuid, though.

david4225y ago

> Things can randomly work for a long time due to duck typing

It's basically like they work by accident. It's not documented what goes in or goes out, so someone throws some data into a function and if it doesn't break then consider it success. And any future person that has to make a change has to untangle that whole mess.

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