diff --git a/brood/src/commands/ingest.rs b/brood/src/commands/ingest.rs
index cf8e60d..c4c82d5 100644
--- a/brood/src/commands/ingest.rs
+++ b/brood/src/commands/ingest.rs
@@ -6,7 +6,7 @@ use std::path::Path;
 use rustc_hash::FxHashMap;
 use serde::Deserialize;
 
-use crate::data::{AdjacencyList, Link, Page};
+use crate::data::{AdjacencyList, Link, LinkInfo, Page, PageInfo};
 use crate::util;
 
 #[derive(Deserialize)]
@@ -61,7 +61,7 @@ impl Titles {
     }
 }
 
-fn first_stage() -> io::Result<(AdjacencyList<(), ()>, Titles)> {
+fn first_stage() -> io::Result<(AdjacencyList<PageInfo, LinkInfo>, Titles)> {
     let mut titles = Titles::default();
     let mut result = AdjacencyList::default();
 
@@ -71,20 +71,19 @@ fn first_stage() -> io::Result<(AdjacencyList<(), ()>, Titles)> {
 
         result.pages.push(Page {
             link_idx: result.links.len() as u32,
-            id: json_page.id,
-            length: json_page.length,
-            redirect: json_page.redirect.is_some(),
-            title: json_page.title,
-            data: (),
+            data: PageInfo {
+                id: json_page.id,
+                length: json_page.length,
+                redirect: json_page.redirect.is_some(),
+                title: json_page.title,
+            },
         });
 
         for (to, start, end) in json_page.links {
             let to = titles.insert(util::normalize_link(&to));
             result.links.push(Link {
                 to,
-                start,
-                end,
-                data: (),
+                data: LinkInfo { start, end },
             });
         }
 
@@ -100,23 +99,29 @@ fn first_stage() -> io::Result<(AdjacencyList<(), ()>, Titles)> {
 
     result.pages.push(Page {
         link_idx: result.links.len() as u32,
-        id: 0,
-        length: 0,
-        redirect: false,
-        title: "Sentinel page at the end of all pages, Q2AKO3OYzyitmCJURghJ".to_string(),
-        data: (),
+        data: PageInfo {
+            id: 0,
+            length: 0,
+            redirect: false,
+            title: "Sentinel page at the end of all pages, Q2AKO3OYzyitmCJURghJ".to_string(),
+        },
     });
 
     Ok((result, titles))
 }
 
 /// Create map from normalized title to index in pages.
-fn initialize_pages_map(pages: &[Page<()>]) -> FxHashMap<String, u32> {
+fn initialize_pages_map(pages: &[Page<PageInfo>]) -> FxHashMap<String, u32> {
     let mut result = FxHashMap::default();
     for (i, p) in pages.iter().enumerate() {
-        match result.entry(util::normalize_link(&p.title)) {
+        match result.entry(util::normalize_link(&p.data.title)) {
             Entry::Occupied(entry) => {
-                eprintln!("{:?} already exists at index {}", p.title, entry.get());
+                eprintln!(
+                    "{:?} already exists at index {} as {:?}",
+                    p.data.title,
+                    entry.get(),
+                    util::normalize_link(&p.data.title)
+                );
             }
             Entry::Vacant(entry) => {
                 entry.insert(i as u32);
@@ -126,7 +131,10 @@ fn initialize_pages_map(pages: &[Page<()>]) -> FxHashMap<String, u32> {
     result
 }
 
-fn second_stage(first_stage: &AdjacencyList<(), ()>, titles: &Titles) -> AdjacencyList<(), ()> {
+fn second_stage(
+    first_stage: &AdjacencyList<PageInfo, LinkInfo>,
+    titles: &Titles,
+) -> AdjacencyList<PageInfo, LinkInfo> {
     let pages_map = initialize_pages_map(&first_stage.pages);
     let mut result = AdjacencyList::default();
 
diff --git a/brood/src/commands/path.rs b/brood/src/commands/path.rs
index d536108..e137d4b 100644
--- a/brood/src/commands/path.rs
+++ b/brood/src/commands/path.rs
@@ -8,7 +8,7 @@ use crate::util;
 pub fn path(datafile: &Path, from: &str, to: &str) -> io::Result<()> {
     eprintln!(">> Import");
     let mut databuf = BufReader::new(File::open(datafile)?);
-    let mut data = AdjacencyList::read(&mut databuf)?.change_page_data(f32::INFINITY);
+    let data = AdjacencyList::read(&mut databuf)?;
 
     eprintln!(">> Locate from and to");
     let from = util::normalize_link(from);
@@ -17,15 +17,15 @@ pub fn path(datafile: &Path, from: &str, to: &str) -> io::Result<()> {
         .pages
         .iter()
         .enumerate()
-        .filter(|(_, p)| !p.redirect)
-        .find(|(_, p)| util::normalize_link(&p.title) == from)
+        .filter(|(_, p)| !p.data.redirect)
+        .find(|(_, p)| util::normalize_link(&p.data.title) == from)
         .unwrap_or_else(|| panic!("no article called {from}"));
     let (to_i, to_p) = data
         .pages
         .iter()
         .enumerate()
-        .filter(|(_, p)| !p.redirect)
-        .find(|(_, p)| util::normalize_link(&p.title) == to)
+        .filter(|(_, p)| !p.data.redirect)
+        .find(|(_, p)| util::normalize_link(&p.data.title) == to)
         .unwrap_or_else(|| panic!("no article called {to}"));
     dbg!(from_i, from_p, to_i, to_p);
 
diff --git a/brood/src/data.rs b/brood/src/data.rs
index 294d0dd..0520d54 100644
--- a/brood/src/data.rs
+++ b/brood/src/data.rs
@@ -1,7 +1,5 @@
 use std::io::{self, Read, Write};
 
-use serde::{Deserialize, Serialize};
-
 mod ioutil {
     use std::io::{self, Read, Write};
 
@@ -50,23 +48,27 @@ mod ioutil {
     }
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct Page<P> {
-    pub link_idx: u32,
+#[derive(Debug, Clone)]
+pub struct PageInfo {
     pub id: u32,
     pub length: u32,
     pub redirect: bool,
     pub title: String,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct Page<P> {
+    pub link_idx: u32,
     pub data: P,
 }
 
-impl Page<()> {
+impl Page<PageInfo> {
     pub fn write<W: Write>(&self, to: &mut W) -> io::Result<()> {
         ioutil::write_u32(self.link_idx, to)?;
-        ioutil::write_u32(self.id, to)?;
-        ioutil::write_u32(self.length, to)?;
-        ioutil::write_u8(if self.redirect { 1 } else { 0 }, to)?;
-        ioutil::write_str(&self.title, to)?;
+        ioutil::write_u32(self.data.id, to)?;
+        ioutil::write_u32(self.data.length, to)?;
+        ioutil::write_u8(if self.data.redirect { 1 } else { 0 }, to)?;
+        ioutil::write_str(&self.data.title, to)?;
 
         Ok(())
     }
@@ -80,41 +82,42 @@ impl Page<()> {
 
         Ok(Self {
             link_idx,
-            id,
-            length,
-            redirect,
-            title,
-            data: (),
+            data: PageInfo {
+                id,
+                length,
+                redirect,
+                title,
+            },
         })
     }
 }
 
 impl<P> Page<P> {
-    pub fn change_data<P2>(self, data: P2) -> Page<P2> {
+    pub fn change_data<P2>(self, f: &impl Fn(P) -> P2) -> Page<P2> {
         Page {
             link_idx: self.link_idx,
-            id: self.id,
-            length: self.length,
-            redirect: self.redirect,
-            title: self.title,
-            data,
+            data: f(self.data),
         }
     }
 }
 
-#[derive(Debug, Clone, Copy, Serialize, Deserialize)]
-pub struct Link<L> {
-    pub to: u32,
+#[derive(Debug, Clone, Copy)]
+pub struct LinkInfo {
     pub start: u32,
     pub end: u32,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct Link<L> {
+    pub to: u32,
     pub data: L,
 }
 
-impl Link<()> {
+impl Link<LinkInfo> {
     pub fn write<W: Write>(&self, to: &mut W) -> io::Result<()> {
         ioutil::write_u32(self.to, to)?;
-        ioutil::write_u32(self.start, to)?;
-        ioutil::write_u32(self.end, to)?;
+        ioutil::write_u32(self.data.start, to)?;
+        ioutil::write_u32(self.data.end, to)?;
 
         Ok(())
     }
@@ -126,31 +129,35 @@ impl Link<()> {
 
         Ok(Self {
             to,
-            start,
-            end,
-            data: (),
+            data: LinkInfo { start, end },
         })
     }
 }
 
-impl<P> Link<P> {
-    pub fn change_data<P2>(self, data: P2) -> Link<P2> {
+impl<L> Link<L> {
+    pub fn change_data<L2>(self, f: &impl Fn(L) -> L2) -> Link<L2> {
         Link {
             to: self.to,
-            start: self.start,
-            end: self.end,
-            data,
+            data: f(self.data),
         }
     }
 }
 
-#[derive(Debug, Default, Serialize, Deserialize)]
 pub struct AdjacencyList<P, L> {
     pub pages: Vec<Page<P>>,
     pub links: Vec<Link<L>>,
 }
 
-impl AdjacencyList<(), ()> {
+impl<P, L> Default for AdjacencyList<P, L> {
+    fn default() -> Self {
+        Self {
+            pages: Default::default(),
+            links: Default::default(),
+        }
+    }
+}
+
+impl AdjacencyList<PageInfo, LinkInfo> {
     pub fn write<W: Write>(&self, to: &mut W) -> io::Result<()> {
         ioutil::write_u32(self.pages.len() as u32, to)?;
         ioutil::write_u32(self.links.len() as u32, to)?;
@@ -182,23 +189,21 @@ impl AdjacencyList<(), ()> {
 
         Ok(Self { pages, links })
     }
-}
 
-impl<P, L> AdjacencyList<P, L> {
     pub fn check_consistency(&self) {
         // Check that all types are large enough
         assert!(self.pages.len() <= u32::MAX as usize, "pages len");
         assert!(self.links.len() <= u32::MAX as usize, "links len");
         for page in &self.pages {
             assert!(page.link_idx <= u32::MAX as u32, "page link_idx");
-            assert!(page.id <= u32::MAX as u32, "page id");
-            assert!(page.length <= u32::MAX as u32, "page length");
-            assert!(page.title.len() <= u8::MAX as usize, "page title len");
+            assert!(page.data.id <= u32::MAX as u32, "page id");
+            assert!(page.data.length <= u32::MAX as u32, "page length");
+            assert!(page.data.title.len() <= u8::MAX as usize, "page title len");
         }
         for link in &self.links {
             assert!(link.to <= u32::MAX as u32, "link to");
-            assert!(link.start <= u32::MAX as u32, "link start");
-            assert!(link.end <= u32::MAX as u32, "link end");
+            assert!(link.data.start <= u32::MAX as u32, "link start");
+            assert!(link.data.end <= u32::MAX as u32, "link end");
         }
 
         // Check that all links contain valid indices
@@ -209,12 +214,14 @@ impl<P, L> AdjacencyList<P, L> {
             }
         }
     }
+}
 
-    pub fn change_page_data<P2: Clone>(self, data: P2) -> AdjacencyList<P2, L> {
+impl<P, L> AdjacencyList<P, L> {
+    pub fn change_page_data<P2: Clone>(self, page_f: &impl Fn(P) -> P2) -> AdjacencyList<P2, L> {
         let pages = self
             .pages
             .into_iter()
-            .map(|p| p.change_data(data.clone()))
+            .map(|p| p.change_data(page_f))
             .collect::<Vec<_>>();
 
         AdjacencyList {
@@ -223,11 +230,11 @@ impl<P, L> AdjacencyList<P, L> {
         }
     }
 
-    pub fn change_link_data<L2: Clone>(self, data: L2) -> AdjacencyList<P, L2> {
+    pub fn change_link_data<L2: Clone>(self, link_f: &impl Fn(L) -> L2) -> AdjacencyList<P, L2> {
         let links = self
             .links
             .into_iter()
-            .map(|l| l.change_data(data.clone()))
+            .map(|l| l.change_data(link_f))
             .collect::<Vec<_>>();
 
         AdjacencyList {