def x := (0xFFFF : UInt8) That compiles with no errors, which I find surprising given Lean’s focus on proving correctness. Is there a good reason for this or is it simply an oversight? Also what does it do at runtime? Bonus question: is there a more elegant way to write a UInt8 literal? E.g. […]

Suppose I have this code:

Suppose I have this code:

Suppose I have this code:

Suppose I have this code:

I ran this program, and was very surprised that it type checked:

With this definition:

With this definition:

With this definition:

As elementary as it is, let me ask the following question.
Given the theorem below, how does the proof function express the case the proposition p does not hold?
The implication, interpreted in its classical meaning, should still hold in this case.