lean4-htt/tests/lean/run/3710.lean
Marc Huisinga 9d427fdfcf
feat: "try this" messages with support for interactivity (#10524)
This PR adds support for interactivity to the combined "try this"
messages that were introduced in #9966. In doing so, it moves the link
to apply a suggestion to a separate `[apply]` button in front of the
suggestion. Hints with diffs remain unchanged, as they did not
previously support interacting with terms in the diff, either.

<img width="379" height="256" alt="Suggestion with interactive message"
src="https://github.com/user-attachments/assets/7838ebf6-0613-46e7-bc88-468a05acbf51"
/>
2025-10-13 13:39:03 +00:00

34 lines
1 KiB
Text

def Set := Nat → Prop
namespace Set
def singleton (a : Nat) : Set := fun b ↦ b = a
def compl (s : Set) : Set := fun x ↦ ¬ s x
@[simp]
theorem compl_iff (s : Set) (x : Nat) : s.compl x ↔ ¬ s x := Iff.rfl
@[simp]
theorem singleton_iff {a b : Nat} : singleton b a ↔ a = b := Iff.rfl
open Classical
noncomputable def indicator (s : Set) (x : Nat) : Nat := if s x then 1 else 0
@[simp] -- remove `simp` attribute --> works (and the trace changes)
theorem indicator_of {s : Set} {a : Nat} (h : s a) : indicator s a = 1 := if_pos h
@[simp]
theorem indicator_of_not {s : Set} {a : Nat} (h : ¬ s a) : indicator s a = 0 := if_neg h
/--
info: Try this:
[apply] simp only [compl_iff, singleton_iff, not_true_eq_false, not_false_eq_true, indicator_of_not]
-/
#guard_msgs in
theorem test : indicator (compl <| singleton 0) 0 = 0 := by
simp? -- should not leave out `singleton_iff`
theorem test' : indicator (compl <| singleton 0) 0 = 0 := by
simp only [compl_iff, singleton_iff, not_true_eq_false, not_false_eq_true, indicator_of_not]