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378 points todsacerdoti | 1 comments | 22 Aug 25 07:08 UTC | HN request time: 0.209s | source
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mensetmanusman ◴[22 Aug 25 13:18 UTC] No.44984308[source]▶
Not being a programmer, I have a question.

Can any program be broken down into functions and functions of functions that have inputs and outputs so that they can be verified if they are working?

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1. pentamassiv ◴[22 Aug 25 14:15 UTC] No.44984968[source]▶
In theory you cannot even say for all programs and all inputs if the program will finish the calculation [0]. In practice you often can break it down but the number of combinations of input is what makes it impossible to test everything. Most developers try to keep individual functions as small as possible to understand them easier. You can use math to do formal verification, but that gets difficult with real programs too.

[0] https://en.wikipedia.org/wiki/Halting_problem