lean4-htt/tests/lean/run/955.lean
Leonardo de Moura 9ee529e5ce fix: use PSum instead of Sum when using well-founded recursion
See new test for example that did not work with `Sum` because type
alpha was `Sort u`.
2022-02-17 16:14:34 -08:00

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namespace Ex2
mutual
def isEven : Nat → Bool
| 0 => true
| n+1 => isOdd n
def isOdd : Nat → Bool
| 0 => false
| n+1 => isEven n
end
termination_by _ n =>
match n with
| _ => n
end Ex2
namespace Ex3
mutual
def isEven : Nat → Bool
| 0 => true
| n+1 => isOdd n
def isOdd : Nat → Bool
| 0 => false
| n+1 => isEven n
end
termination_by' measure (fun n => match n with | PSum.inl n => n | PSum.inr n => n)
end Ex3