diff -r 3f3e00e81755 -r edb95d2b83cc src/mapping.rs
--- a/src/mapping.rs	Sat Nov 09 20:54:32 2024 -0500
+++ b/src/mapping.rs	Sun Nov 10 09:02:57 2024 -0500
@@ -74,6 +74,14 @@
     fn differential(&self, x : X) -> Self::Derivative;
 }
 
+impl<'g, X, G : Differentiable<X>> Differentiable<X> for &'g G {
+    type Derivative = G::Derivative;
+    #[inline]
+    fn differential(&self, x : X) -> Self::Derivative {
+        (*self).differential(x)
+    }
+}
+
 /// A differentiable mapping from `Domain` to [`Mapping::Codomain`], with differentials
 /// `Differential`.
 ///
@@ -99,7 +107,7 @@
           + for<'a> Differentiable<&'a Domain,Derivative=Derivative> {
     type DerivativeDomain = Derivative;
     type Differential = Differential<Domain, Self>;
-    type DifferentialRef<'b> = Differential<Domain, Ref<'b, Self>> where Self : 'b;
+    type DifferentialRef<'b> = Differential<Domain, &'b Self> where Self : 'b;
     
     /// Form the differential mapping of `self`.
     fn diff(self) -> Self::Differential {
@@ -108,7 +116,7 @@
 
     /// Form the differential mapping of `self`.
     fn diff_ref(&self) -> Self::DifferentialRef<'_> {
-        Differential{ g : Ref(self), _space : PhantomData }
+        Differential{ g : self, _space : PhantomData }
     }
 }
 
@@ -171,6 +179,12 @@
     _space : PhantomData<X>
 }
 
+impl<X, G : DifferentiableMapping<X>> Differential<X, G> {
+    pub fn base_fn(&self) -> &G {
+        &self.g
+    }
+}
+
 impl<X, G : DifferentiableMapping<X>> Apply<X> for Differential<X, G> {
     type Output = G::DerivativeDomain;
 
@@ -258,9 +272,9 @@
     }
 
     /// Flatten the codomain from [`Loc`]`<F, 1>` to `F`.
-    fn slice_codomain_ref(&self, slice : usize) -> SlicedCodomain<X, F, Ref<'_, Self>, N> {
+    fn slice_codomain_ref(&self, slice : usize) -> SlicedCodomain<X, F, &'_ Self, N> {
         assert!(slice < N);
-        SlicedCodomain{ g : Ref(self), slice, _phantoms : PhantomData }
+        SlicedCodomain{ g : self, slice, _phantoms : PhantomData }
     }
 }
 
@@ -268,23 +282,3 @@
 SliceCodomain<X, F, N>
 for G {}
 
-
-/// Helper struct for doing operations on references of mappings while avoiding
-/// conflicting implementations that `&'g G` would cause.
-pub struct Ref<'g, G>(&'g G);
-
-impl<'g, X, G : Apply<X>> Apply<X> for Ref<'g, G> {
-    type Output = G::Output;
-    #[inline]
-    fn apply(&self, x : X) -> Self::Output {
-        self.0.apply(x)
-    }
-}
-
-impl<'g, X, G : Differentiable<X>> Differentiable<X> for Ref<'g, G> {
-    type Derivative = G::Derivative;
-    #[inline]
-    fn differential(&self, x : X) -> Self::Derivative {
-        self.0.differential(x)
-    }
-}