diff --git a/packages/effect-fc/src/Lens.ts b/packages/effect-fc/src/Lens.ts
index 79a8f5a..50f1319 100644
--- a/packages/effect-fc/src/Lens.ts
+++ b/packages/effect-fc/src/Lens.ts
@@ -81,7 +81,18 @@ export const unwrap = <A, ER, EW, RR, RW, E1, R1>(
 })
 
 
-export const map = <A, ER, EW, RR, RW, B>(
+export const map: {
+    <A, ER, EW, RR, RW, B>(
+        self: Lens<A, ER, EW, RR, RW>,
+        get: (a: NoInfer<A>) => B,
+        set: (a: NoInfer<A>, b: B) => NoInfer<A>,
+    ): Lens<B, ER, EW, RR, RW>
+    <A, ER, EW, RR, RW, B>(
+        get: (a: NoInfer<A>) => B,
+        set: (a: NoInfer<A>, b: B) => NoInfer<A>,
+        self: Lens<A, ER, EW, RR, RW>,
+    ): Lens<B, ER, EW, RR, RW>
+} = Function.dual(3, <A, ER, EW, RR, RW, B>(
     self: Lens<A, ER, EW, RR, RW>,
     get: (a: NoInfer<A>) => B,
     set: (a: NoInfer<A>, b: B) => NoInfer<A>,
@@ -93,9 +104,20 @@ export const map = <A, ER, EW, RR, RW, B>(
     ) => self.modify(a =>
         Effect.flatMap(f(get(a)), ([c, next]) => Effect.succeed([c, set(a, next)]))
     ),
-})
+}))
 
-export const mapEffect = <A, ER, EW, RR, RW, B, EGet = never, RGet = never, ESet = never, RSet = never>(
+export const mapEffect: {
+    <A, ER, EW, RR, RW, B, EGet = never, RGet = never, ESet = never, RSet = never>(
+        self: Lens<A, ER, EW, RR, RW>,
+        get: (a: NoInfer<A>) => Effect.Effect<B, EGet, RGet>,
+        set: (a: NoInfer<A>, b: B) => Effect.Effect<NoInfer<A>, ESet, RSet>,
+    ): Lens<B, ER | EGet, EW | ESet, RR | RGet, RW | RSet>
+    <A, ER, EW, RR, RW, B, EGet = never, RGet = never, ESet = never, RSet = never>(
+        get: (a: NoInfer<A>) => Effect.Effect<B, EGet, RGet>,
+        set: (a: NoInfer<A>, b: B) => Effect.Effect<NoInfer<A>, ESet, RSet>,
+        self: Lens<A, ER, EW, RR, RW>,
+    ): Lens<B, ER | EGet, EW | ESet, RR | RGet, RW | RSet>
+} = Function.dual(3, <A, ER, EW, RR, RW, B, EGet = never, RGet = never, ESet = never, RSet = never>(
     self: Lens<A, ER, EW, RR, RW>,
     get: (a: NoInfer<A>) => Effect.Effect<B, EGet, RGet>,
     set: (a: NoInfer<A>, b: B) => Effect.Effect<NoInfer<A>, ESet, RSet>,
@@ -114,7 +136,7 @@ export const mapEffect = <A, ER, EW, RR, RW, B, EGet = never, RGet = never, ESet
             ),
         )
     )),
-})
+}))
 
 
 export const get = <A, ER, EW, RR, RW>(self: Lens<A, ER, EW, RR, RW>): Effect.Effect<A, ER, RR> => self.get