Control.Comonad.Transformerless.Store

data Store s a

Constructors

• Store (s -> a) s

Instances

• Functor (Store s)
• Extend (Store s)
• Comonad (Store s)

runStore :: forall a s. Store s a -> Tuple (s -> a) s

store :: forall a s. (s -> a) -> s -> Store s a

peek :: forall a s. s -> Store s a -> a

1. Law: peek (pos x) x = extract x
2. Proof:
3. RHS := extract (f, s) = f s
4. LHS := peek (pos (f, s)) (f, s) =
5. peek s (f, s) =
6. peek s (f, _) = f s

pos :: forall a s. Store s a -> s

1. Law: pos (extend _ x) = pos x
2. Proof:
3. RHS := pos (_, s)
4. LHS := pos (extend _ (f, s)) =
5. pos (extend _ (_, s)) =
6. pos (_, s)