diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,14 @@
 # Changelog
 
+## 0.2.0.0 — 2026-04-07
+
+- Add `Functor` instance for `Service req` — use `fmap` to transform successful responses
+- Add `Profunctor` instance for `Service` — use `dimap`/`lmap` to adapt request and response types
+- Add `contramapService` and `dimapService` as named synonyms for `lmap` and `dimap`
+- `mapService` is now a synonym for `fmap`
+- New dependency: `profunctors`
+- Adopt `(&)` from `Data.Function` as idiomatic style in docs, tests, and examples
+
 ## 0.1.0.0 — 2026-04-06
 
 - Initial release
diff --git a/src/Tower.hs b/src/Tower.hs
--- a/src/Tower.hs
+++ b/src/Tower.hs
@@ -7,15 +7,16 @@
 -- Build composable middleware stacks for any service type.
 --
 -- @
+-- import Data.Function (('&'))
 -- import Tower
 --
 -- -- Define a service
 -- let svc = 'Service' $ \\req -> pure (Right (process req))
 --
--- -- Compose middleware
--- let robust = 'withRetry' ('constantBackoff' 3 1.0)
---            . 'withTimeout' 5000
---            $ svc
+-- -- Compose middleware using '&'
+-- let robust = svc
+--            '&' 'withTimeout' 5000
+--            '&' 'withRetry' ('constantBackoff' 3 1.0)
 -- @
 --
 -- All errors are returned as @'Either' 'ServiceError' response@ — no exceptions
@@ -25,6 +26,8 @@
     Service(..)
   , Middleware
   , mapService
+  , contramapService
+  , dimapService
   , composeMiddleware
     -- * Errors
   , ServiceError(..)
diff --git a/src/Tower/Middleware/Tracing.hs b/src/Tower/Middleware/Tracing.hs
--- a/src/Tower/Middleware/Tracing.hs
+++ b/src/Tower/Middleware/Tracing.hs
@@ -9,9 +9,10 @@
 -- 'TracingConfig' to control the span name, kind, and attribute extraction.
 --
 -- @
+-- import Data.Function (('&'))
 -- let config = ('defaultTracingConfig' "my-service")
 --       { 'tracingReqAttrs' = \\req s -> addAttribute s "my.attr" (show req) }
--- client |> 'withTracingConfig' tracer config
+-- svc '&' 'withTracingConfig' tracer config
 -- @
 module Tower.Middleware.Tracing
   ( TracingConfig(..)
diff --git a/src/Tower/Service.hs b/src/Tower/Service.hs
--- a/src/Tower/Service.hs
+++ b/src/Tower/Service.hs
@@ -10,14 +10,23 @@
   ( Service(..)
   , Middleware
   , mapService
+  , contramapService
+  , dimapService
   , composeMiddleware
   ) where
 
+import Data.Profunctor (Profunctor(..))
 import Tower.Error (ServiceError)
 
 -- | A service transforms a request into an effectful response.
 -- This is the fundamental building block — middleware wraps services.
 --
+-- 'Service' is a 'Functor' in its response type and a 'Profunctor' over
+-- both request and response types. Use 'fmap' to transform responses,
+-- 'lmap' to transform requests, or 'dimap' to transform both — useful for
+-- lifting a @Service Http.Request Http.Response@ into a
+-- @Service MyBinding.SomeRequest MyBinding.SomeResponse@.
+--
 -- @
 -- let echoService = 'Service' $ \\req -> pure (Right req)
 -- result <- 'runService' echoService "hello"
@@ -28,6 +37,14 @@
     -- ^ Execute the service with a request, returning either an error or a response.
   }
 
+instance Functor (Service req) where
+  fmap f (Service run) = Service $ \req -> fmap (fmap f) (run req)
+
+instance Profunctor Service where
+  dimap f g (Service run) = Service $ \req -> fmap (fmap g) (run (f req))
+  lmap f (Service run) = Service (run . f)
+  rmap = fmap
+
 -- | Middleware wraps a service to add behavior (retry, timeout, logging, etc.)
 --
 -- A middleware is simply a function from 'Service' to 'Service':
@@ -39,6 +56,8 @@
 
 -- | Transform the response of a service, leaving errors unchanged.
 --
+-- This is a synonym for 'fmap' on the 'Functor' instance.
+--
 -- @
 -- let svc = 'Service' $ \\_ -> pure (Right 10)
 -- let doubled = 'mapService' (* 2) svc
@@ -46,7 +65,34 @@
 -- -- result == Right 20
 -- @
 mapService :: (a -> b) -> Service req a -> Service req b
-mapService f (Service run) = Service $ \req -> fmap (fmap f) (run req)
+mapService = fmap
+
+-- | Transform the request type of a service.
+--
+-- This is a synonym for 'lmap' on the 'Profunctor' instance.
+--
+-- @
+-- let svc :: Service String String
+--     svc = 'Service' $ \\req -> pure (Right req)
+--     adapted = 'contramapService' show svc  -- now Service Int String
+-- result <- 'runService' adapted 42
+-- -- result == Right \"42\"
+-- @
+contramapService :: (a -> b) -> Service b res -> Service a res
+contramapService = lmap
+
+-- | Transform both request and response types of a service.
+--
+-- This is a synonym for 'dimap' on the 'Profunctor' instance.
+-- Useful for adapting a generic service to a domain-specific API:
+--
+-- @
+-- let httpSvc :: Service Http.Request Http.Response
+-- let apiSvc = 'dimapService' toHttpRequest fromHttpResponse httpSvc
+-- -- apiSvc :: Service MyRequest MyResponse
+-- @
+dimapService :: (a -> b) -> (c -> d) -> Service b c -> Service a d
+dimapService = dimap
 
 -- | Compose two middleware, applying the outer first, then the inner.
 --
diff --git a/test/Tower/Middleware/CircuitBreakerSpec.hs b/test/Tower/Middleware/CircuitBreakerSpec.hs
--- a/test/Tower/Middleware/CircuitBreakerSpec.hs
+++ b/test/Tower/Middleware/CircuitBreakerSpec.hs
@@ -10,6 +10,7 @@
 import Tower.Service
 import Tower.Error
 import Tower.Error.Testing ()
+import Data.Function ((&))
 import Tower.Middleware.CircuitBreaker
 
 spec :: Spec
@@ -24,7 +25,7 @@
       breaker <- newCircuitBreaker
       let svc :: Service () String
           svc = Service $ \_ -> pure (Right "ok")
-          wrapped = withCircuitBreaker config breaker svc
+          wrapped = svc & withCircuitBreaker config breaker
       result <- runService wrapped ()
       result `shouldBe` Right "ok"
       getCircuitBreakerState breaker >>= (`shouldBe` Closed)
@@ -36,7 +37,7 @@
           svc = Service $ \_ -> do
             modifyIORef' callCount (+ 1)
             pure (Left (CustomError "fail"))
-          wrapped = withCircuitBreaker config breaker svc
+          wrapped = svc & withCircuitBreaker config breaker
       -- 2 failures, threshold is 3
       _ <- runService wrapped ()
       _ <- runService wrapped ()
@@ -48,7 +49,7 @@
       breaker <- newCircuitBreaker
       let svc :: Service () String
           svc = Service $ \_ -> pure (Left (CustomError "fail"))
-          wrapped = withCircuitBreaker config breaker svc
+          wrapped = svc & withCircuitBreaker config breaker
       -- 3 failures = threshold
       _ <- runService wrapped ()
       _ <- runService wrapped ()
@@ -62,7 +63,7 @@
           failSvc = Service $ \_ -> do
             modifyIORef' callCount (+ 1)
             pure (Left (CustomError "fail"))
-          wrapped = withCircuitBreaker config breaker failSvc
+          wrapped = failSvc & withCircuitBreaker config breaker
       -- Trip the breaker
       _ <- runService wrapped ()
       _ <- runService wrapped ()
@@ -80,7 +81,7 @@
       breaker <- newCircuitBreaker
       let svc :: Service () String
           svc = Service $ \_ -> pure (Left (CustomError "fail"))
-          wrapped = withCircuitBreaker fastConfig breaker svc
+          wrapped = svc & withCircuitBreaker fastConfig breaker
       -- Trip the breaker
       _ <- runService wrapped ()
       _ <- runService wrapped ()
@@ -104,7 +105,7 @@
             if n < 3
               then pure (Left (CustomError "fail"))
               else pure (Right "recovered")
-          wrapped = withCircuitBreaker fastConfig breaker svc
+          wrapped = svc & withCircuitBreaker fastConfig breaker
       -- Trip the breaker (3 failures)
       _ <- runService wrapped ()
       _ <- runService wrapped ()
@@ -128,7 +129,7 @@
             if n == 1  -- second call succeeds
               then pure (Right "ok")
               else pure (Left (CustomError "fail"))
-          wrapped = withCircuitBreaker config breaker svc
+          wrapped = svc & withCircuitBreaker config breaker
       -- Fail once
       _ <- runService wrapped ()
       -- Succeed — resets counter
diff --git a/test/Tower/Middleware/FilterSpec.hs b/test/Tower/Middleware/FilterSpec.hs
--- a/test/Tower/Middleware/FilterSpec.hs
+++ b/test/Tower/Middleware/FilterSpec.hs
@@ -7,6 +7,7 @@
 import Tower.Service
 import Tower.Error
 import Tower.Error.Testing ()
+import Data.Function ((&))
 import Tower.Middleware.Filter
 
 spec :: Spec
@@ -15,21 +16,21 @@
     it "allows matching requests through" $ do
       let svc :: Service String String
           svc = Service $ \_ -> pure (Right "ok")
-          filtered = withFilter (const True) svc
+          filtered = svc & withFilter (const True)
       result <- runService filtered "request"
       result `shouldBe` Right "ok"
 
     it "rejects non-matching requests" $ do
       let svc :: Service String String
           svc = Service $ \_ -> pure (Right "ok")
-          filtered = withFilter (const False) svc
+          filtered = svc & withFilter (const False)
       result <- runService filtered "request"
       result `shouldBe` Left (CustomError "Request filtered out")
 
     it "filters based on request properties" $ do
       let svc :: Service String String
           svc = Service $ \_ -> pure (Right "ok")
-          onlyGet = withFilter (== "GET") svc
+          onlyGet = svc & withFilter (== "GET")
       getResult <- runService onlyGet "GET"
       postResult <- runService onlyGet "POST"
       getResult `shouldBe` Right "ok"
diff --git a/test/Tower/Middleware/HedgeSpec.hs b/test/Tower/Middleware/HedgeSpec.hs
--- a/test/Tower/Middleware/HedgeSpec.hs
+++ b/test/Tower/Middleware/HedgeSpec.hs
@@ -10,6 +10,7 @@
 import Tower.Service
 import Tower.Error
 import Tower.Error.Testing ()
+import Data.Function ((&))
 import Tower.Middleware.Hedge
 
 spec :: Spec
@@ -17,7 +18,7 @@
   it "returns result from fast primary without hedging" $ do
     let svc :: Service () String
         svc = Service $ \_ -> pure (Right "fast")
-        hedged = withHedge 1000 svc
+        hedged = svc & withHedge 1000
     result <- runService hedged ()
     result `shouldBe` Right "fast"
 
@@ -31,7 +32,7 @@
               threadDelay 500_000  -- primary: slow
               pure (Right "primary")
             else pure (Right "hedge")  -- hedge: instant
-        hedged = withHedge 50 svc
+        hedged = svc & withHedge 50
     result <- runService hedged ()
     case result of
       Right _ -> pure ()
@@ -44,7 +45,7 @@
           modifyIORef' callCount (+ 1)
           threadDelay 100_000
           pure (Right "done")
-        hedged = withHedge 50 svc
+        hedged = svc & withHedge 50
     _ <- runService hedged ()
     threadDelay 200_000
     count <- readIORef callCount
diff --git a/test/Tower/Middleware/LoggingSpec.hs b/test/Tower/Middleware/LoggingSpec.hs
--- a/test/Tower/Middleware/LoggingSpec.hs
+++ b/test/Tower/Middleware/LoggingSpec.hs
@@ -10,6 +10,7 @@
 import Tower.Service
 import Tower.Error
 import Tower.Error.Testing ()
+import Data.Function ((&))
 import Tower.Middleware.Logging
 
 spec :: Spec
@@ -22,7 +23,7 @@
           Left err  -> "ERR: " <> displayError err
         svc :: Service () Text
         svc = Service $ \_ -> pure (Right "done")
-        logged = withLogging formatter logger svc
+        logged = svc & withLogging formatter logger
     _ <- runService logged ()
     logs <- readIORef logRef
     length logs `shouldBe` 1
@@ -36,7 +37,7 @@
           Left err -> "ERR: " <> displayError err
         svc :: Service () Text
         svc = Service $ \_ -> pure (Left TimeoutError)
-        logged = withLogging formatter logger svc
+        logged = svc & withLogging formatter logger
     _ <- runService logged ()
     logs <- readIORef logRef
     length logs `shouldBe` 1
@@ -47,7 +48,7 @@
         formatter _ _ _ = "ignored"
         svc :: Service () Text
         svc = Service $ \_ -> pure (Right "original")
-        logged = withLogging formatter logger svc
+        logged = svc & withLogging formatter logger
     result <- runService logged ()
     result `shouldBe` Right "original"
 
@@ -57,7 +58,7 @@
         formatter req _ _ = "request=" <> req
         svc :: Service Text Text
         svc = Service $ \_ -> pure (Right "ok")
-        logged = withLogging formatter logger svc
+        logged = svc & withLogging formatter logger
     _ <- runService logged "my-request"
     logs <- readIORef logRef
     head logs `shouldBe` "request=my-request"
diff --git a/test/Tower/Middleware/RetrySpec.hs b/test/Tower/Middleware/RetrySpec.hs
--- a/test/Tower/Middleware/RetrySpec.hs
+++ b/test/Tower/Middleware/RetrySpec.hs
@@ -10,6 +10,7 @@
 import Tower.Service
 import Tower.Error
 import Tower.Error.Testing ()
+import Data.Function ((&))
 import Tower.Middleware.Retry
 
 spec :: Spec
@@ -21,7 +22,7 @@
           svc = Service $ \_ -> do
             modifyIORef' callCount (+ 1)
             pure (Right "ok")
-          retried = withRetry (constantBackoff 3 0) svc
+          retried = svc & withRetry (constantBackoff 3 0)
       result <- runService retried ()
       result `shouldBe` Right "ok"
       readIORef callCount >>= (`shouldBe` 1)
@@ -32,7 +33,7 @@
           svc = Service $ \_ -> do
             modifyIORef' callCount (+ 1)
             pure (Left (CustomError "fail"))
-          retried = withRetry (constantBackoff 3 0) svc
+          retried = svc & withRetry (constantBackoff 3 0)
       result <- runService retried ()
       case result of
         Left (RetryExhausted n _) -> n `shouldBe` 3
@@ -48,7 +49,7 @@
             if n < 2
               then pure (Left (CustomError "transient"))
               else pure (Right "recovered")
-          retried = withRetry (constantBackoff 3 0) svc
+          retried = svc & withRetry (constantBackoff 3 0)
       result <- runService retried ()
       result `shouldBe` Right "recovered"
       readIORef callCount >>= (`shouldBe` 3)  -- 2 failures + 1 success
@@ -59,7 +60,7 @@
           svc = Service $ \_ -> do
             modifyIORef' callCount (+ 1)
             pure (Left (CustomError "fail"))
-          retried = withRetry (constantBackoff 0 0) svc
+          retried = svc & withRetry (constantBackoff 0 0)
       result <- runService retried ()
       case result of
         Left (RetryExhausted 0 _) -> pure ()
diff --git a/test/Tower/Middleware/TimeoutSpec.hs b/test/Tower/Middleware/TimeoutSpec.hs
--- a/test/Tower/Middleware/TimeoutSpec.hs
+++ b/test/Tower/Middleware/TimeoutSpec.hs
@@ -9,6 +9,7 @@
 import Tower.Service
 import Tower.Error
 import Tower.Error.Testing ()
+import Data.Function ((&))
 import Tower.Middleware.Timeout
 
 spec :: Spec
@@ -16,7 +17,7 @@
   it "allows fast requests through" $ do
     let svc :: Service () String
         svc = Service $ \_ -> pure (Right "fast")
-        timed = withTimeout 1000 svc
+        timed = svc & withTimeout 1000
     result <- runService timed ()
     result `shouldBe` Right "fast"
 
@@ -25,13 +26,13 @@
         svc = Service $ \_ -> do
           threadDelay 500_000  -- 500ms
           pure (Right "slow")
-        timed = withTimeout 100 svc  -- 100ms timeout
+        timed = svc & withTimeout 100  -- 100ms timeout
     result <- runService timed ()
     result `shouldBe` Left TimeoutError
 
   it "preserves errors from inner service" $ do
     let svc :: Service () String
         svc = Service $ \_ -> pure (Left (CustomError "inner error"))
-        timed = withTimeout 1000 svc
+        timed = svc & withTimeout 1000
     result <- runService timed ()
     result `shouldBe` Left (CustomError "inner error")
diff --git a/test/Tower/Middleware/TracingSpec.hs b/test/Tower/Middleware/TracingSpec.hs
--- a/test/Tower/Middleware/TracingSpec.hs
+++ b/test/Tower/Middleware/TracingSpec.hs
@@ -12,6 +12,7 @@
 import Tower.Service
 import Tower.Error
 import Tower.Error.Testing ()
+import Data.Function ((&))
 import Tower.Middleware.Tracing
 
 spec :: Spec
@@ -23,7 +24,7 @@
     let config = defaultTracingConfig "test-span"
         svc :: Service () String
         svc = Service $ \_ -> pure (Right "hello")
-        traced = withTracingGlobal testLib config svc
+        traced = svc & withTracingGlobal testLib config
     result <- runService traced ()
     result `shouldBe` Right "hello"
 
@@ -31,7 +32,7 @@
     let config = defaultTracingConfig "test-span"
         svc :: Service () String
         svc = Service $ \_ -> pure (Left TimeoutError)
-        traced = withTracingGlobal testLib config svc
+        traced = svc & withTracingGlobal testLib config
     result <- runService traced ()
     result `shouldBe` Left TimeoutError
 
@@ -42,7 +43,7 @@
         svc = Service $ \_ -> do
           modifyIORef' callCount (+ 1)
           pure (Right "ok")
-        traced = withTracingGlobal testLib config svc
+        traced = svc & withTracingGlobal testLib config
     _ <- runService traced ()
     readIORef callCount >>= (`shouldBe` 1)
 
@@ -51,7 +52,7 @@
           { tracingSpanName = ("span-" <>) }
         svc :: Service Text String
         svc = Service $ \_ -> pure (Right "ok")
-        traced = withTracingGlobal testLib config svc
+        traced = svc & withTracingGlobal testLib config
     result <- runService traced "test"
     result `shouldBe` Right "ok"
 
@@ -61,7 +62,7 @@
           { tracingReqAttrs = \_ _ -> writeIORef hookCalled True }
         svc :: Service () String
         svc = Service $ \_ -> pure (Right "ok")
-        traced = withTracingGlobal testLib config svc
+        traced = svc & withTracingGlobal testLib config
     _ <- runService traced ()
     readIORef hookCalled >>= (`shouldBe` True)
 
@@ -71,7 +72,7 @@
           { tracingResAttrs = \_ _ -> writeIORef hookCalled True }
         svc :: Service () String
         svc = Service $ \_ -> pure (Right "ok")
-        traced = withTracingGlobal testLib config svc
+        traced = svc & withTracingGlobal testLib config
     _ <- runService traced ()
     readIORef hookCalled >>= (`shouldBe` True)
 
@@ -81,7 +82,7 @@
           { tracingResAttrs = \_ _ -> writeIORef hookCalled True }
         svc :: Service () String
         svc = Service $ \_ -> pure (Left (CustomError "fail"))
-        traced = withTracingGlobal testLib config svc
+        traced = svc & withTracingGlobal testLib config
     _ <- runService traced ()
     readIORef hookCalled >>= (`shouldBe` False)
 
diff --git a/test/Tower/Middleware/TransformSpec.hs b/test/Tower/Middleware/TransformSpec.hs
--- a/test/Tower/Middleware/TransformSpec.hs
+++ b/test/Tower/Middleware/TransformSpec.hs
@@ -8,6 +8,7 @@
 import Tower.Service
 import Tower.Error
 import Tower.Error.Testing ()
+import Data.Function ((&))
 import Tower.Middleware.Transform
 
 spec :: Spec
@@ -16,26 +17,26 @@
     it "transforms the request before passing to inner service" $ do
       let svc :: Service String String
           svc = Service $ \req -> pure (Right req)
-          transformed = withMapRequestPure (++ "!") svc
+          transformed = svc & withMapRequestPure (++ "!")
       result <- runService transformed "hello"
       result `shouldBe` Right "hello!"
 
     it "does not alter the response" $ do
       let svc :: Service String String
           svc = Service $ \_ -> pure (Right "response")
-          transformed = withMapRequestPure (++ "!") svc
+          transformed = svc & withMapRequestPure (++ "!")
       result <- runService transformed "request"
       result `shouldBe` Right "response"
 
     it "composes multiple transforms (right-to-left)" $ do
       let svc :: Service String String
           svc = Service $ \req -> pure (Right req)
-          transformed = withMapRequestPure (++ "3")
-                      . withMapRequestPure (++ "2")
-                      . withMapRequestPure (++ "1")
-                      $ svc
+          transformed = svc
+                      & withMapRequestPure (++ "1")
+                      & withMapRequestPure (++ "2")
+                      & withMapRequestPure (++ "3")
       result <- runService transformed "base"
-      -- Middleware composes right-to-left: 1 applied first, then 2, then 3
+      -- Middleware applies left-to-right: 1 applied first, then 2, then 3
       result `shouldBe` Right "base321"
 
   describe "withMapRequest" $ do
@@ -43,9 +44,9 @@
       counter <- newIORef (0 :: Int)
       let svc :: Service String String
           svc = Service $ \req -> pure (Right req)
-          transformed = withMapRequest (\req -> do
+          transformed = svc & withMapRequest (\req -> do
             n <- atomicModifyIORef' counter (\c -> (c + 1, c))
-            pure (req ++ "-" ++ show n)) svc
+            pure (req ++ "-" ++ show n))
       r1 <- runService transformed "req"
       r2 <- runService transformed "req"
       r1 `shouldBe` Right "req-0"
@@ -54,6 +55,6 @@
     it "passes through errors from inner service" $ do
       let svc :: Service String String
           svc = Service $ \_ -> pure (Left (CustomError "fail"))
-          transformed = withMapRequest (\req -> pure (req ++ "!")) svc
+          transformed = svc & withMapRequest (\req -> pure (req ++ "!"))
       result <- runService transformed "hello"
       result `shouldBe` Left (CustomError "fail")
diff --git a/test/Tower/Middleware/ValidateSpec.hs b/test/Tower/Middleware/ValidateSpec.hs
--- a/test/Tower/Middleware/ValidateSpec.hs
+++ b/test/Tower/Middleware/ValidateSpec.hs
@@ -7,6 +7,7 @@
 import Tower.Service
 import Tower.Error
 import Tower.Error.Testing ()
+import Data.Function ((&))
 import Tower.Middleware.Validate
 
 spec :: Spec
@@ -14,34 +15,34 @@
   it "passes responses that return Nothing" $ do
     let svc :: Service () String
         svc = Service $ \_ -> pure (Right "ok")
-        validated = withValidate (const Nothing) svc
+        validated = svc & withValidate (const Nothing)
     result <- runService validated ()
     result `shouldBe` Right "ok"
 
   it "rejects responses that return Just" $ do
     let svc :: Service () String
         svc = Service $ \_ -> pure (Right "bad")
-        validated = withValidate (\_ -> Just "validation failed") svc
+        validated = svc & withValidate (\_ -> Just "validation failed")
     result <- runService validated ()
     result `shouldBe` Left (CustomError "validation failed")
 
   it "passes through errors from inner service" $ do
     let svc :: Service () String
         svc = Service $ \_ -> pure (Left TimeoutError)
-        validated = withValidate (const (Just "should not trigger")) svc
+        validated = svc & withValidate (const (Just "should not trigger"))
     result <- runService validated ()
     result `shouldBe` Left TimeoutError
 
   it "can inspect the response value" $ do
     let svc :: Service () Int
         svc = Service $ \_ -> pure (Right 42)
-        validated = withValidate (\n -> if n > 100 then Just "too big" else Nothing) svc
+        validated = svc & withValidate (\n -> if n > 100 then Just "too big" else Nothing)
     result <- runService validated ()
     result `shouldBe` Right 42
 
   it "rejects based on response value" $ do
     let svc :: Service () Int
         svc = Service $ \_ -> pure (Right 200)
-        validated = withValidate (\n -> if n > 100 then Just "too big" else Nothing) svc
+        validated = svc & withValidate (\n -> if n > 100 then Just "too big" else Nothing)
     result <- runService validated ()
     result `shouldBe` Left (CustomError "too big")
diff --git a/test/Tower/ServiceSpec.hs b/test/Tower/ServiceSpec.hs
--- a/test/Tower/ServiceSpec.hs
+++ b/test/Tower/ServiceSpec.hs
@@ -6,6 +6,7 @@
 
 import Tower.Service
 import Tower.Error
+import Data.Function ((&))
 import Tower.Error.Testing ()
 
 spec :: Spec
@@ -26,14 +27,14 @@
     it "transforms successful responses" $ do
       let svc :: Service () Int
           svc = Service $ \_ -> pure (Right 10)
-          mapped = mapService (* 3) svc
+          mapped = svc & mapService (* 3)
       result <- runService mapped ()
       result `shouldBe` Right 30
 
     it "passes through errors unchanged" $ do
       let svc :: Service () Int
           svc = Service $ \_ -> pure (Left TimeoutError)
-          mapped = mapService (* 3) svc
+          mapped = svc & mapService (* 3)
       result <- runService mapped ()
       result `shouldBe` Left TimeoutError
 
diff --git a/tower-hs.cabal b/tower-hs.cabal
--- a/tower-hs.cabal
+++ b/tower-hs.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           tower-hs
-version:        0.1.0.0
+version:        0.2.0.0
 synopsis:       Composable service middleware for Haskell, inspired by Rust's Tower
 description:    tower-hs provides a composable middleware abstraction for any service type.
                 Build middleware stacks with retry, timeout, circuit breaker, and more — all with
@@ -53,6 +53,7 @@
       async ==2.2.*
     , base >=4.14 && <5
     , hs-opentelemetry-api ==0.3.*
+    , profunctors ==5.6.*
     , stm ==2.5.*
     , text >=2.0 && <2.2
     , time >=1.11 && <1.15