23 ms·

I’m surprised anyone thinks types make unit tests redundant. I can know a function returns a value adhering to the correct interface, sure, but that doesn’t tel

• seanmcdirmid 3y ago
  It could happen given a sufficiently powerful type system…a type system no one would probably want to use (given that you would write more type-finessing code than real code, you might as well be programming with a theorem prover).
• LispSporks22 3y ago
  When I was a Haskell noob there was this weird meme being propagated that if it compiles, it’s correct.
  • tome 3y ago
    It's possible you heard that (there are 227 hits for that phrase on Google) but more likely you heard "if it compiles, it works" (35,000 hits). "If it compiles, it’s correct" is obviously false, and no one should be saying it about Haskell code. "If it compiles, it works" is true in certain contexts and for suitably weak definition of "works" (such as, behaves in a sensible way and provides a sensible answer, just not necessarily a correct one) and is an experience attested to by many, many Haskell programmers.
• kelnos 3y ago
  Types make some tests redundant. I've seen unit tests in Python code bases that were simply there to make sure that a function did something sane if a value of the wrong type was passed to it. I think it's absolutely certain that, to achieve the same level of confidence in your code, you need more unit tests for, say, a Python code base, than for a Java code base.