def guardM {m : Type → Type v} [Monad m] [Alternative m] (p : m Bool) : m Unit

Executes guard p in m; fails via Alternative.failure if p returns false, otherwise returns Unit.unit.

Equations

• guardM p = do let x ← p guard (x = true)

@[implicit_reducible]

def IO.Ref.toMonadStateOf {α : Type} (ref : Ref α) : MonadStateOf α IO

Lift an IO.Ref α into a MonadStateOf α IO instance, forwarding get/set/modifyGet directly to the ref.

Equations

• ref.toMonadStateOf = { get := ST.Ref.get ref, set := ST.Ref.set ref, modifyGet := fun {α_1 : Type} => ST.Ref.modifyGet ref }