Counting Sheeps with Contracts in Python
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Counting Sheeps with Contracts in Python
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Re: Counting Sheeps with Contracts in Python
#2Hello everyone, I'm starting a new blog where I'm trying to mix my passion and experience for safe programming in critical contexts, and my (over)use of Python, and other techs that are used in... less safe contexts. The "investment hypothesis" if you will is that pieces of tech used daily in critical systems could see a broader use if they stopped being hidden behind mumbo jumbo, bad UX, and general lack of consideration for the common developper. In this blog I'll try to go and discuss fuzzing, contracts, why not some amount of lightweight proofing... and to mix them with application that are hopefully fun and nice to study.
This first post is about counting sheeps, with a design-by-contract twist.
Let me know what you guys think, it's my first blog at all, so I'm a taker for all matters of feedback, as long as it comes from the heart that is ;)
Re: Counting Sheeps with Contracts in Python
#3This isn't meant as a dig, I'm genuinely curious: how is this not simply imposing static typing in python?
Re: Counting Sheeps with Contracts in Python
#4This isn't meant as a dig, I'm genuinely curious: how is this not simply imposing static typing in python?
The pre and post conditions are checked at runtime. Also, typically static type sytems are not expressive enough to statically check more than relatively basic pre and post conditions, even in languages with advanced type systems like Haskell or Scala.
Re: Counting Sheeps with Contracts in Python
#5At this point just use Java instead.
Re: Counting Sheeps with Contracts in Python
#6Cool stuff! Might be fun to integrate with a type validation library like Pydantic or Msgspec to provide in-line coercion/assertion.
What is the performance hit like? I could see these getting pretty expensive (but correctness is invaluable). Seems like it would be great for something like aws lambda in python where you have already decided performance isn't an utmost priority and scrutability is difficult, so any correctness you can bolt on is a boon.
Re: Counting Sheeps with Contracts in Python
#7They don't even mention the Eiffel language [1] while writing about Design by Contract?
[1] https://en.wikipedia.org/wiki/Eiffel_(programming_language)
Re: Counting Sheeps with Contracts in Python
#8At this point just use Java instead.
I agree 100%
Re: Counting Sheeps with Contracts in Python
#9This isn't meant as a dig, I'm genuinely curious: how is this not simply imposing static typing in python?
You can have preconditions that check stuff not related to typing (e.g: check that a connection is open before calling the function).
Re: Counting Sheeps with Contracts in Python
#10One of the most 'nice' thing about contract systems is automating blame checking in higher-order code. They handle the lambda/method param wrapping and blame direction assignment for you, which is annoying to do via manual assertions.
I didn't see a link to DBC, is that in there? Or some other use of contracts that is hard via just asserts, like in test amplification?
We are always looking for ways to improve our Python codebase, and I hadn't expected to see modern investment here!