Add lenses for List1

src/Data/List1/Lens.idr

@@ -0,0 +1,51 @@
+module Data.List1.Lens
+
+import Data.List1
+import Data.Profunctor
+import public Control.Lens
+import Data.Tuple.Lens
+
+%default total
+
+||| An isomorphism between a list and its reverse.
+public export
+reversed : Iso (List1 a) (List1 b) (List1 a) (List1 b)
+reversed = iso reverse reverse
+
+
+public export
+cons_ : Iso (List1 a) (List1 b) (a, List a) (b, List b)
+cons_ = iso (\(x:::xs) => (x,xs)) (uncurry (:::))
+
+public export
+head_ : Lens' (List1 a) a
+head_ = cons_ . fst_
+
+public export
+tail_ : Lens' (List1 a) (List a)
+tail_ = cons_ . snd_
+
+public export
+snoc_ : Iso (List1 a) (List1 b) (List a, a) (List b, b)
+snoc_ = iso unsnoc (uncurry lappend . mapSnd singleton)
+
+public export
+init_ : Lens' (List1 a) (List a)
+init_ = snoc_ . fst_
+
+public export
+last_ : Lens' (List1 a) a
+last_ = snoc_ . snd_
+
+
+public export
+Ixed Nat a (List1 a) where
+  ix = element
+
+public export
+Each (List1 a) (List1 b) a b where
+  each = traversed
+
+public export
+Num i => IEach i (List1 a) (List1 b) a b where
+  ieach = itraversed