An Optional is a collection of zero or one elements.
Force unwrapping is [0].
Fight me
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It used to be actual peano numbers but the errors were bad. github.com/diesel-rs/dies
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Languages like Idris or Lean have much better error reporting for this stuff. Can be very useful, but you do need good error reporting.
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But do they tell you when your peano needs to be tuned?
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I just define a `has_coe ℕ 🎹` instance!