The "and this is why it matters" is often left to be inferred by the reader. ;) General kinds of reasons include "preventing (whole classes of) mistakes" or "wr

The "and this is why it matters" is often left to be inferred by the reader. ;) General kinds of reasons include "preventing (whole classes of) mistakes" or "writing even more reusable code" or "making things fast". I know the kind of thread you mean -- it happened to me last weekend https://www.reddit.com/r/haskell/comments/2tl8v1/making_propellor_safer_with_gadts_and_type/ https://www.reddit.com/r/haskell/comments/2tl8v1/making_prop... . But I really appreciated those suggestions about even more clever ways to make my code better, even though I have so far not incorporated any of them. It helped me learn more about the shape of a space I'm only starting to explore, and since I'm exploring it for real-world reasons, the very abstract and hifaluting suggestions were easy to relate back to real-world concerns. Which is a great way to learn. And I suspect several of the commenters there were commenting for exactly that reason -- if there's one thing the haskell community excells at, it's noticing when someone is in a receptive state (or coaxing them into one), and helping them learn.