diff --git a/src/layout.rs b/src/layout.rs
index 838ac2b..ebc10c6 100644
--- a/src/layout.rs
+++ b/src/layout.rs
@@ -3,7 +3,7 @@ use std::rc::Rc;
 use geo::geometry::Point;
 
 use crate::math::Circle;
-use crate::mesh::{Mesh, Index, IndexRTreeWrapper, DotIndex, SegIndex, BendIndex};
+use crate::mesh::{Mesh, TaggedIndex, RTreeWrapper, DotIndex, SegIndex, BendIndex};
 use crate::rules::{Rules, Conditions};
 use crate::primitive::Primitive;
 use crate::weight::{Weight, DotWeight, SegWeight, BendWeight};
@@ -48,7 +48,7 @@ impl Layout {
         let tangent_points = math::tangent_point_pair(from_circle, from_cw, to_circle, Some(cw));
 
         let head = self.extend_head(head, tangent_points.0);
-        self.route_seg_bend(head, Index::Dot(around), tangent_points.1, cw, width)
+        self.route_seg_bend(head, TaggedIndex::Dot(around), tangent_points.1, cw, width)
     }
 
     pub fn route_around_bend(&mut self, head: Head, around: BendIndex, cw: bool, width: f64) -> Head {
@@ -67,7 +67,7 @@ impl Layout {
         let tangent_points = math::tangent_point_pair(from_circle, from_cw, to_circle, Some(cw));
 
         let head = self.extend_head(head, tangent_points.0);
-        self.route_seg_bend(head, Index::Bend(around), tangent_points.1, cw, width)
+        self.route_seg_bend(head, TaggedIndex::Bend(around), tangent_points.1, cw, width)
     }
 
     pub fn route_end(&mut self, head: Head, to: DotIndex, width: f64) {
@@ -81,7 +81,7 @@ impl Layout {
         };
 
         let to_circle = Circle {
-            pos: self.mesh.weight(Index::Dot(to)).as_dot().unwrap().circle.pos,
+            pos: self.mesh.dot_weight(to).circle.pos,
             r: 0.0,
         };
 
@@ -92,14 +92,13 @@ impl Layout {
         self.add_seg(head.dot, to, width);
     }
 
-    fn route_seg_bend(&mut self, head: Head, around: Index, to: Point, cw: bool, width: f64) -> Head {
+    fn route_seg_bend(&mut self, head: Head, around: TaggedIndex, to: Point, cw: bool, width: f64) -> Head {
         let head = self.route_seg(head, to, width);
-        let bend_to = self.add_dot(*self.mesh.primitive(Index::Dot(head.dot)).weight.as_dot().unwrap());
-        let from_primitive = self.mesh.primitive(Index::Dot(head.dot));
-        let net = from_primitive.weight.as_dot().unwrap().net;
+        let bend_to = self.add_dot(self.mesh.dot_weight(head.dot));
+        let net = self.mesh.dot_weight(head.dot).net;
 
         let mut layer = around;
-        while let Index::Bend(..) = layer {
+        while let TaggedIndex::Bend(..) = layer {
             layer = self.mesh.weight(layer).as_bend().unwrap().around;
         }
         let center = *layer.as_dot().unwrap();
@@ -109,10 +108,9 @@ impl Layout {
     }
 
     fn route_seg(&mut self, head: Head, to: Point, width: f64) -> Head {
-        let from_primitive = self.mesh.primitive(Index::Dot(head.dot));
-        let net = from_primitive.weight.as_dot().unwrap().net;
+        let net = self.mesh.dot_weight(head.dot).net;
 
-        assert!(width <= from_primitive.weight.as_dot().unwrap().circle.r * 2.0);
+        assert!(width <= self.mesh.dot_weight(head.dot).circle.r * 2.0);
 
         let to_index = self.mesh.add_dot(DotWeight {
             net,
@@ -134,7 +132,7 @@ impl Layout {
 
         match maybe_bend {
             Some(bend) => {
-                let head_around = self.mesh.weight(Index::Bend(bend)).as_bend().unwrap().around;
+                let head_around = self.mesh.bend_weight(bend).around;
 
                 match self.mesh.weight(head_around) {
                     Weight::Dot(..) => self.dot_guidecircle(*head_around.as_dot().unwrap(), width + 5.0, conditions),
@@ -143,7 +141,7 @@ impl Layout {
                 }
             },
             None => Circle {
-                pos: self.mesh.weight(Index::Dot(head.dot)).as_dot().unwrap().circle.pos,
+                pos: self.mesh.dot_weight(head.dot).circle.pos,
                 r: 0.0,
             },
         }
@@ -151,13 +149,13 @@ impl Layout {
 
     fn head_cw(&self, head: &Head) -> Option<bool> {
         match head.bend {
-            Some(bend) => Some(self.mesh.weight(Index::Bend(bend)).as_bend().unwrap().cw,),
+            Some(bend) => Some(self.mesh.bend_weight(bend).cw),
             None => None,
         }
     }
 
     fn dot_guidecircle(&self, dot: DotIndex, width: f64, conditions: Conditions) -> Circle {
-        let circle = self.mesh.weight(Index::Dot(dot)).as_dot().unwrap().circle;
+        let circle = self.mesh.dot_weight(dot).circle;
         Circle {
             pos: circle.pos,
             r: circle.r + width + self.rules.ruleset(conditions).clearance.min,
@@ -165,15 +163,15 @@ impl Layout {
     }
 
     fn bend_guidecircle(&self, bend: BendIndex, width: f64, conditions: Conditions) -> Circle {
-        let mut layer = Index::Bend(bend);
+        let mut layer = TaggedIndex::Bend(bend);
         let mut r = width + self.rules.ruleset(conditions).clearance.min;
 
-        while let Index::Bend(..) = layer {
+        while let TaggedIndex::Bend(..) = layer {
             layer = self.mesh.weight(layer).as_bend().unwrap().around;
             r += 5.0 + self.mesh.primitive(layer).width();
         }
 
-        let circle = self.primitive(layer).weight.as_dot().unwrap().circle;
+        let circle = self.mesh.weight(layer).as_dot().unwrap().circle;
         Circle {
             pos: circle.pos,
             r: circle.r - 5.0 + r,
@@ -187,20 +185,20 @@ impl Layout {
             head
             // No assertion for now because we temporarily use floats.
 
-            //println!("{:?} {:?}", self.mesh.weight(Index::Dot(from)).as_dot().unwrap().circle.pos, to);
-            //assert!(self.mesh.weight(Index::Dot(from)).as_dot().unwrap().circle.pos == to);
+            //println!("{:?} {:?}", self.mesh.weight(TaggedIndex::Dot(from)).as_dot().unwrap().circle.pos, to);
+            //assert!(self.mesh.weight(TaggedIndex::Dot(from)).as_dot().unwrap().circle.pos == to);
         }
     }
 
     fn extend_head_bend(&mut self, head: Head, to: Point) -> Head {
         let bend = head.bend.unwrap();
-        let dot_weight = *self.mesh.weight(Index::Dot(head.dot)).as_dot().unwrap();
-        let bend_weight = *self.mesh.weight(Index::Bend(bend)).as_bend().unwrap();
+        let dot_weight = self.mesh.dot_weight(head.dot);
+        let bend_weight = self.mesh.bend_weight(bend);
 
-        let fixed_dot: Index = self.mesh.dot_neighbors(Index::Bend(bend))
+        let fixed_dot: TaggedIndex = self.mesh.neighboring_dots(TaggedIndex::Bend(bend))
             .into_iter()
-            .filter(|neighbor| *neighbor != Index::Dot(head.dot))
-            .collect::<Vec<Index>>()[0];
+            .filter(|neighbor| *neighbor != TaggedIndex::Dot(head.dot))
+            .collect::<Vec<TaggedIndex>>()[0];
 
         self.mesh.remove_bend(bend);
         self.mesh.remove_dot(head.dot);
@@ -225,8 +223,7 @@ impl Layout {
     }
 
     pub fn add_seg(&mut self, from: DotIndex, to: DotIndex, width: f64) -> SegIndex {
-        let from_primitive = self.mesh.primitive(Index::Dot(from));
-        let net = from_primitive.weight.as_dot().unwrap().net;
+        let net = self.mesh.dot_weight(from).net;
         self.mesh.add_seg(from, to, SegWeight {net, width})
     }
 
@@ -234,7 +231,7 @@ impl Layout {
         self.mesh.primitives()
     }
 
-    pub fn primitive(&self, index: Index) -> Primitive {
+    pub fn primitive(&self, index: TaggedIndex) -> Primitive {
         return self.mesh.primitive(index);
     }
 
diff --git a/src/mesh.rs b/src/mesh.rs
index b2f575b..9880142 100644
--- a/src/mesh.rs
+++ b/src/mesh.rs
@@ -1,3 +1,4 @@
+use std::marker::PhantomData;
 use enum_as_inner::EnumAsInner;
 use petgraph::stable_graph::{StableUnGraph, NodeIndex, EdgeIndex};
 use petgraph::visit::EdgeRef;
@@ -7,22 +8,62 @@ use rstar::primitives::GeomWithData;
 use crate::primitive::Primitive;
 use crate::weight::{Weight, DotWeight, SegWeight, BendWeight};
 
-pub type DotIndex = NodeIndex<u32>;
-pub type SegIndex = EdgeIndex<u32>;
-pub type BendIndex = EdgeIndex<u32>;
+
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub struct Index<Ix, T> {
+    index: Ix,
+    marker: PhantomData<T>,
+}
+
+impl<Ix, T> Index<Ix, T> {
+    pub fn new(index: Ix) -> Self {
+        Self {
+            index,
+            marker: PhantomData,
+        }
+    }
+}
+
+pub trait Tag {
+    fn tag(&self) -> TaggedIndex;
+}
+
+pub type DotIndex = Index<NodeIndex<usize>, DotWeight>;
+
+impl Tag for DotIndex {
+    fn tag(&self) -> TaggedIndex {
+        TaggedIndex::Dot(*self)
+    }
+}
+
+pub type SegIndex = Index<EdgeIndex<usize>, SegWeight>;
+
+impl Tag for SegIndex {
+    fn tag(&self) -> TaggedIndex {
+        TaggedIndex::Seg(*self)
+    }
+}
+
+pub type BendIndex = Index<EdgeIndex<usize>, BendWeight>;
+
+impl Tag for BendIndex {
+    fn tag(&self) -> TaggedIndex {
+        TaggedIndex::Bend(*self)
+    }
+}
 
 #[derive(Debug, EnumAsInner, Copy, Clone, PartialEq)]
-pub enum Index {
+pub enum TaggedIndex {
     Dot(DotIndex),
     Seg(SegIndex),
     Bend(BendIndex),
 }
 
-pub type IndexRTreeWrapper = GeomWithData<Primitive, Index>;
+pub type RTreeWrapper = GeomWithData<Primitive, TaggedIndex>;
 
 pub struct Mesh {
-    pub rtree: RTree<IndexRTreeWrapper>,
-    pub graph: StableUnGraph<Weight, Weight, u32>,
+    pub rtree: RTree<RTreeWrapper>,
+    pub graph: StableUnGraph<Weight, Weight, usize>,
 }
 
 impl Mesh {
@@ -34,63 +75,63 @@ impl Mesh {
     }
 
     pub fn add_dot(&mut self, weight: DotWeight) -> DotIndex {
-        let dot_index = self.graph.add_node(Weight::Dot(weight));
-        let index = Index::Dot(dot_index);
-        self.rtree.insert(IndexRTreeWrapper::new(self.primitive(index), index));
+        let dot_index = DotIndex::new(self.graph.add_node(Weight::Dot(weight)));
+        let index = TaggedIndex::Dot(dot_index);
+        self.rtree.insert(RTreeWrapper::new(self.primitive(index), index));
         dot_index
     }
 
     pub fn remove_dot(&mut self, dot: DotIndex) {
-        self.rtree.remove(&IndexRTreeWrapper::new(self.primitive(Index::Dot(dot)), Index::Dot(dot)));
-        self.graph.remove_node(dot);
+        self.rtree.remove(&RTreeWrapper::new(self.primitive(TaggedIndex::Dot(dot)), TaggedIndex::Dot(dot)));
+        self.graph.remove_node(dot.index);
     }
 
     pub fn add_seg(&mut self, from: DotIndex, to: DotIndex, weight: SegWeight) -> SegIndex {
-        let seg_index = self.graph.add_edge(from, to, Weight::Seg(weight));
-        let index = Index::Seg(seg_index);
-        self.rtree.insert(IndexRTreeWrapper::new(self.primitive(index), index));
+        let seg_index = SegIndex::new(self.graph.add_edge(from.index, to.index, Weight::Seg(weight)));
+        let index = TaggedIndex::Seg(seg_index);
+        self.rtree.insert(RTreeWrapper::new(self.primitive(index), index));
         seg_index
     }
 
     pub fn remove_seg(&mut self, seg: SegIndex) {
-        self.rtree.remove(&IndexRTreeWrapper::new(self.primitive(Index::Seg(seg)), Index::Seg(seg)));
-        self.graph.remove_edge(seg);
+        self.rtree.remove(&RTreeWrapper::new(self.primitive(TaggedIndex::Seg(seg)), TaggedIndex::Seg(seg)));
+        self.graph.remove_edge(seg.index);
     }
 
     pub fn add_bend(&mut self, from: DotIndex, to: DotIndex, weight: BendWeight) -> BendIndex {
-        let bend_index = self.graph.add_edge(from, to, Weight::Bend(weight));
-        let index = Index::Bend(bend_index);
-        self.rtree.insert(IndexRTreeWrapper::new(self.primitive(index), index));
+        let bend_index = BendIndex::new(self.graph.add_edge(from.index, to.index, Weight::Bend(weight)));
+        let index = TaggedIndex::Bend(bend_index);
+        self.rtree.insert(RTreeWrapper::new(self.primitive(index), index));
         bend_index
     }
 
     pub fn remove_bend(&mut self, bend: BendIndex) {
-        self.rtree.remove(&IndexRTreeWrapper::new(self.primitive(Index::Bend(bend)), Index::Bend(bend)));
-        self.graph.remove_edge(bend);
+        self.rtree.remove(&RTreeWrapper::new(self.primitive(TaggedIndex::Bend(bend)), TaggedIndex::Bend(bend)));
+        self.graph.remove_edge(bend.index);
     }
 
     pub fn primitives(&self) -> Box<dyn Iterator<Item=Primitive> + '_> {
         Box::new(self.rtree.iter().map(|wrapper| self.primitive(wrapper.data)))
     }
 
-    pub fn primitive(&self, index: Index) -> Primitive {
+    pub fn primitive(&self, index: TaggedIndex) -> Primitive {
         Primitive {
             weight: self.weight(index),
             dot_neighbor_weights:
-                self.dot_neighbors(index)
+                self.neighboring_dots(index)
                     .into_iter()
                     .map(|index| *self.weight(index).as_dot().unwrap())
                     .collect(),
             around_weight: match index {
-                Index::Bend(bend_index) => {
+                TaggedIndex::Bend(bend_index) => {
                     Some(self.weight((*self.weight(index).as_bend().unwrap()).around))
                 },
                 _ => None,
             },
             focus: match index {
-                Index::Bend(bend_index) => {
+                TaggedIndex::Bend(bend_index) => {
                     let mut layer = index;
-                    while let Index::Bend(..) = layer {
+                    while let TaggedIndex::Bend(..) = layer {
                         layer = self.weight(layer).as_bend().unwrap().around;
                     }
                     Some(self.weight(layer).as_dot().unwrap().circle.pos)
@@ -100,22 +141,38 @@ impl Mesh {
         }
     }
 
-    pub fn dot_neighbors(&self, index: Index) -> Vec<Index> {
+    pub fn neighboring_dots(&self, index: TaggedIndex) -> Vec<TaggedIndex> {
         match index {
-            Index::Dot(node_index) =>
-                return self.graph.neighbors(node_index).map(|ni| Index::Dot(ni)).collect(),
-            Index::Seg(edge_index) | Index::Bend(edge_index) => {
+            TaggedIndex::Dot(DotIndex {index: node_index, ..}) =>
+                return self.graph.neighbors(node_index)
+                    .map(|ni| TaggedIndex::Dot(Index::new(ni))).collect(),
+            TaggedIndex::Seg(SegIndex {index: edge_index, ..})
+            | TaggedIndex::Bend(BendIndex {index: edge_index, ..}) => {
                 let endpoints = self.graph.edge_endpoints(edge_index).unwrap();
-                return vec![Index::Dot(endpoints.0), Index::Dot(endpoints.1)]
+                return vec![TaggedIndex::Dot(DotIndex::new(endpoints.0)),
+                            TaggedIndex::Dot(DotIndex::new(endpoints.1))]
             }
         }
     }
 
-    pub fn weight(&self, index: Index) -> Weight {
+    pub fn dot_weight(&self, dot: DotIndex) -> DotWeight {
+        *self.weight(dot.tag()).as_dot().unwrap()
+    }
+
+    pub fn seg_weight(&self, seg: SegIndex) -> SegWeight {
+        *self.weight(seg.tag()).as_seg().unwrap()
+    }
+
+    pub fn bend_weight(&self, bend: BendIndex) -> BendWeight {
+        *self.weight(bend.tag()).as_bend().unwrap()
+    }
+
+    pub fn weight(&self, index: TaggedIndex) -> Weight {
         match index {
-            Index::Dot(node_index) =>
+            TaggedIndex::Dot(DotIndex {index: node_index, ..}) =>
                 *self.graph.node_weight(node_index).unwrap(),
-            Index::Seg(edge_index) | Index::Bend(edge_index) =>
+            TaggedIndex::Seg(SegIndex {index: edge_index, ..})
+            | TaggedIndex::Bend(BendIndex {index: edge_index, ..}) =>
                 *self.graph.edge_weight(edge_index).unwrap(),
         }
     }
diff --git a/src/weight.rs b/src/weight.rs
index ffebc87..9ef720c 100644
--- a/src/weight.rs
+++ b/src/weight.rs
@@ -1,5 +1,5 @@
 use enum_as_inner::EnumAsInner;
-use crate::{math::Circle, mesh::{Index, DotIndex}};
+use crate::{math::Circle, mesh::{DotIndex, TaggedIndex}};
 
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct DotWeight {
@@ -10,7 +10,7 @@ pub struct DotWeight {
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct BendWeight {
     pub net: i32,
-    pub around: Index,
+    pub around: TaggedIndex,
     pub center: DotIndex,
     pub cw: bool,
 }