b5122b6a7b
This change * moves `termination_by` and `decreasing_by` next to the function they apply to * simplify the syntax of `termination_by` * apply the `decreasing_by` goal to all goals at once, for better interactive use. See the section in `RELEASES.md` for more details and migration advise. This is a hard breaking change, requiring developers to touch every `termination_by` in their code base. We decided to still do it as a hard-breaking change, because supporting both old and new syntax at the same time would be non-trivial, and not save that much. Moreover, this requires changes to some metaprograms that developers might have written, and supporting both syntaxes at the same time would make _their_ migration harder.
46 lines
998 B
Text
46 lines
998 B
Text
inductive Foo (n : Nat) : Type
|
|
| foo (t: Foo n): Foo n
|
|
|
|
namespace Foo
|
|
inductive Bar: Foo n → Prop
|
|
|
|
theorem ex₁ {s: Foo n} (H: s.Bar): True := by
|
|
cases h₁ : s
|
|
case foo s' =>
|
|
cases h₂ : n; sorry
|
|
have: Bar s' := sorry
|
|
exact ex₁ this
|
|
termination_by sizeOf s
|
|
|
|
theorem ex₂
|
|
{s: Foo n}
|
|
(H: s.Bar):
|
|
True := by
|
|
generalize hs': s = s'
|
|
match s' with
|
|
| foo s' =>
|
|
have: Bar s' := sorry
|
|
have hterm: sizeOf s' < sizeOf s := by simp_all_arith
|
|
exact ex₂ this
|
|
termination_by sizeOf s
|
|
|
|
theorem ex₃ {s: Foo n} (H: s.Bar): True := by
|
|
cases h₁ : s
|
|
case foo s' =>
|
|
match n with
|
|
| 0 => sorry
|
|
| _ =>
|
|
have: Bar s' := sorry
|
|
exact ex₃ this
|
|
termination_by sizeOf s
|
|
|
|
-- it works
|
|
theorem ex₄ {s: Foo n} (H: s.Bar): True := by
|
|
match s with
|
|
| foo s' =>
|
|
match n with
|
|
| 0 => sorry
|
|
| _ =>
|
|
have: Bar s' := sorry
|
|
exact ex₄ this
|
|
termination_by sizeOf s
|