tracking issue for change in behaviour in `@[simp] def`
semorrison opened this issue · comments
Back in Lean 3, @[simp] def f only unfolded suitably applied appearances of f. In Lean 4, it means it can be unfolded unapplied.
This resulted in many @[simp] attributes being removed from definitions, and replaced by explicit @[simp] lemmas.
This issue is a tracking issue for places where adaptations were required for this that may warrant further investigation. Often during the port this was worked around using @[eqns], but with changes to the generation of equation lemmas this approach has become less reliable.
Please feel free to edit the description to provide better/more detailed explanation of the change.
Some instances of #11119 should perhaps be updated to point here.