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  "path": "/t/knownnat-indexed-vectors/14099?page=2#post_24",
  "publishedAt": "2026-05-14T19:00:09.000Z",
  "site": "https://discourse.haskell.org",
  "tags": [
    "comfort-array"
  ],
  "textContent": "mixphix:\n\n> Are there `Num` instances for any of these Finite types?\n\nIs the product of two rings a ring? If not, there should not be such an instance in general. `Finite n` can be a field if `n` is prime, if I am not mistaken. But why would you want a `Num` instance on the index set anyways?\n\nmixphix:\n\n> This approach has the advantage that it doesn’t “segfault” if indexing past the length\n\nIf you are not striving for type-safe indexing, why pursue this approach at all?\n\nI forgot to mention Henning Thielemann’s linear algebra ecosystem with lapack, comfort-array and its shapes.",
  "title": "KnownNat-indexed vectors"
}