Note about Mathlib/Init/

The files in Mathlib/Init are leftovers from the port from Mathlib3. (They contain content moved from lean3 itself that Mathlib needed but was not moved to lean4.)

We intend to move all the content of these files out into the main Mathlib directory structure. Contributions assisting with this are appreciated.

Decidable and Monad instances for List not (yet) in Batteries

instance List.instMonad : Monad List

Equations

• List.instMonad = Monad.mk

@[simp]

theorem List.pure_def {α : Type u} (a : α) : pure a = [a]

instance List.instLawfulMonad : LawfulMonad List

Equations

• List.instLawfulMonad = ⋯

instance List.instAlternative : Alternative List

Equations

• List.instAlternative = Alternative.mk @List.nil fun {α : Type u} (l : List α) (l' : Unit → List α) => l.append (l' ())