remove future type param

tower/src/util/and_then.rs

@@ -1,4 +1,3 @@
-use std::marker::PhantomData;
 use std::task::{Context, Poll};
 
 use futures_core::TryFuture;
@@ -10,24 +9,19 @@ use tower_service::Service;
 ///
 /// [`and_then`]: crate::util::ServiceExt::and_then
 #[derive(Clone, Debug)]
-pub struct AndThen<S, F, Fut> {
+pub struct AndThen<S, F> {
     inner: S,
     f: F,
-    _fut: PhantomData<Fut>,
 }
 
-impl<S, F, Fut> AndThen<S, F, Fut> {
+impl<S, F> AndThen<S, F> {
     /// Creates a new `AndThen` service.
     pub fn new(inner: S, f: F) -> Self {
-        AndThen {
-            f,
-            inner,
-            _fut: Default::default(),
-        }
+        AndThen { f, inner }
     }
 }
 
-impl<S, F, Request, Fut> Service<Request> for AndThen<S, F, Fut>
+impl<S, F, Request, Fut> Service<Request> for AndThen<S, F>
 where
     S: Service<Request>,
     F: FnOnce(S::Response) -> Fut + Clone,
@@ -50,32 +44,27 @@ where
 ///
 /// [`Layer`]: tower_layer::Layer
 #[derive(Debug)]
-pub struct AndThenLayer<F, Fut> {
+pub struct AndThenLayer<F> {
     f: F,
-    _fut: PhantomData<Fut>,
 }
 
-impl<F, Fut> AndThenLayer<F, Fut> {
+impl<F> AndThenLayer<F> {
     /// Creates a new [`AndThenLayer`] layer.
     pub fn new(f: F) -> Self {
-        AndThenLayer {
-            f,
-            _fut: Default::default(),
-        }
+        AndThenLayer { f }
     }
 }
 
-impl<S, F, Fut> Layer<S> for AndThenLayer<F, Fut>
+impl<S, F> Layer<S> for AndThenLayer<F>
 where
     F: Clone,
 {
-    type Service = AndThen<S, F, Fut>;
+    type Service = AndThen<S, F>;
 
     fn layer(&self, inner: S) -> Self::Service {
         AndThen {
             f: self.f.clone(),
             inner,
-            _fut: Default::default(),
         }
     }
 }

tower/src/util/mod.rs

@@ -92,12 +92,13 @@ pub trait ServiceExt<Request>: tower_service::Service<Request> {
     {
         CallAll::new(self, reqs)
     }
-    
-    fn and_then<F, Fut>(self, f: F) -> AndThen<Self, F, Fut>
+
+    fn and_then<F>(self, f: F) -> AndThen<Self, F>
     where
-    Self: Sized,
-        F: FnOnce(Self::Response) -> Fut + Clone {
-            AndThen::new(self, f)
+        Self: Sized,
+        F: Clone,
+    {
+        AndThen::new(self, f)
     }
 
     /// Maps this service's response value to a different value. This does not