lean2/tests/lean/unfold_rec3.lean

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open nat
definition nrec [recursor] := @nat.rec
definition myadd x y :=
nrec y (λ n r, succ r) x
theorem myadd_zero : ∀ n, myadd n 0 = n :=
begin
intro n, induction n with n ih,
reflexivity,
esimp [myadd],
state,
rewrite ih
end