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import Mathlib.Lean.Expr.Basic
import Lean.Elab.Tactic.Basic
/-! # `rfl` tactic
Added `withReducible` to prevent `rfl` proving stuff like `n + 0 = n`.
-/
namespace MyNat
open Lean Meta Elab Tactic
-- @[match_pattern] def MyNat.rfl {α : Sort u} {a : α} : Eq a a := Eq.refl a
/-- Modified `rfl` tactic.
`rfl` closes goals of the form `A = A`.
Note that teh version for this game is somewhat weaker than the real one. -/
syntax (name := rfl) "rfl" : tactic
@[tactic MyNat.rfl] def evalRfl : Tactic := fun _ =>
liftMetaTactic fun mvarId => do withReducible <| mvarId.refl; pure []