diff --git a/src/serde2.rs b/src/serde2.rs
new file mode 100644
index 00000000..f0df9e84
--- /dev/null
+++ b/src/serde2.rs
@@ -0,0 +1,684 @@
+use std::io::IoResult;
+use std::io;
+use std::collections::TreeMap;
+
+///////////////////////////////////////////////////////////////////////////////
+
+trait Serialize<S, R> {
+    fn serialize(&self, state: &mut S) -> R;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+trait Serializer<S, R> {
+    fn hash<T: Serialize<S, R>>(&self, value: &T) -> R;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+trait Visitor<S, R> {
+    fn visit(&mut self, state: &mut S) -> Option<R>;
+
+    fn size_hint(&self) -> (uint, Option<uint>) {
+        (0, None)
+    }
+}
+
+trait SerializeState<R> {
+    fn serialize_int(&mut self, value: int) -> R;
+
+    fn serialize_str(&mut self, value: &'static str) -> R;
+
+    fn serialize_seq<
+        T: Serialize<Self, R>,
+        Iter: Iterator<T>
+    >(&mut self, iter: Iter) -> R;
+
+    fn serialize_seq_elt<
+        T: Serialize<Self, R>
+    >(&mut self, first: bool, value: T) -> R;
+
+    fn serialize_tuple<
+        V: Visitor<Self, R>
+    >(&mut self, visitor: V) -> R;
+
+    fn serialize_tuple_struct<
+        V: Visitor<Self, R>
+    >(&mut self, name: &'static str, mut visitor: V) -> R;
+
+    fn serialize_enum<
+        V: Visitor<Self, R>
+    >(&mut self, name: &'static str, variant: &'static str, visitor: V) -> R;
+
+    fn serialize_map<
+        K: Serialize<Self, R>,
+        V: Serialize<Self, R>,
+        Iter: Iterator<(K, V)>
+    >(&mut self, iter: Iter) -> R;
+
+    fn serialize_map_elt<
+        K: Serialize<Self, R>,
+        V: Serialize<Self, R>
+    >(&mut self, first: bool, key: K, value: V) -> R;
+
+    fn serialize_struct<
+        V: Visitor<Self, R>
+    >(&mut self, name: &'static str, visitor: V) -> R;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+impl<S: SerializeState<R>, R> Serialize<S, R> for int {
+    fn serialize(&self, state: &mut S) -> R {
+        state.serialize_int(*self)
+    }
+}
+
+impl<S: SerializeState<R>, R> Serialize<S, R> for &'static str {
+    fn serialize(&self, state: &mut S) -> R {
+        state.serialize_str(*self)
+    }
+}
+
+impl<
+    S: SerializeState<R>,
+    R,
+    T: Serialize<S, R>
+> Serialize<S, R> for Vec<T> {
+    fn serialize(&self, state: &mut S) -> R {
+        state.serialize_seq(self.iter())
+    }
+}
+
+impl<
+    S: SerializeState<R>,
+    R,
+    K: Serialize<S, R> + Ord,
+    V: Serialize<S, R>
+> Serialize<S, R> for TreeMap<K, V> {
+    fn serialize(&self, state: &mut S) -> R {
+        state.serialize_map(self.iter())
+    }
+}
+
+impl<
+    'a,
+    S: SerializeState<R>,
+    R,
+    T0: Serialize<S, R>,
+    T1: Serialize<S, R>
+> Serialize<S, R> for (T0, T1) {
+    fn serialize(&self, state: &mut S) -> R {
+        state.serialize_tuple(Tuple2Serialize { value: self, state: 0 })
+    }
+}
+
+struct Tuple2Serialize<'a, T0, T1> {
+    value: &'a (T0, T1),
+    state: uint,
+}
+
+impl<
+    'a,
+    S: SerializeState<R>,
+    R,
+    T0: Serialize<S, R>,
+    T1: Serialize<S, R>
+> Visitor<S, R> for Tuple2Serialize<'a, T0, T1> {
+    fn visit(&mut self, state: &mut S) -> Option<R> {
+        match self.state {
+            0 => {
+                self.state += 1;
+                let (ref value, _) = *self.value;
+                Some(state.serialize_seq_elt(true, value))
+            }
+            1 => {
+                self.state += 1;
+                let (_, ref value) = *self.value;
+                Some(state.serialize_seq_elt(false, value))
+            }
+            _ => {
+                None
+            }
+        }
+    }
+
+    fn size_hint(&self) -> (uint, Option<uint>) {
+        let size = 2 - self.state;
+        (size, Some(size))
+    }
+}
+
+impl<
+    'a,
+    S: SerializeState<R>,
+    R,
+    T: Serialize<S, R>
+> Serialize<S, R> for &'a T {
+    fn serialize(&self, state: &mut S) -> R {
+        (**self).serialize(state)
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+#[deriving(Show)]
+enum Token {
+    Int(int),
+    Str(&'static str),
+    SeqStart(uint),
+    MapStart(uint),
+    StructStart(&'static str, uint),
+    End,
+}
+
+trait TokenState<R>: SerializeState<R> {
+    fn serialize(&mut self, token: Token) -> R;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+struct GatherTokens {
+    tokens: Vec<Token>,
+}
+
+impl GatherTokens {
+    fn new() -> GatherTokens {
+        GatherTokens {
+            tokens: Vec::new(),
+        }
+    }
+
+    fn unwrap(self) -> Vec<Token> {
+        self.tokens
+    }
+}
+
+impl TokenState<()> for GatherTokens {
+    fn serialize(&mut self, token: Token) -> () {
+        self.tokens.push(token);
+    }
+}
+
+impl SerializeState<()> for GatherTokens {
+    fn serialize_int(&mut self, value: int) -> () {
+        self.serialize(Int(value))
+    }
+
+    fn serialize_str(&mut self, value: &'static str) -> () {
+        self.serialize(Str(value))
+    }
+
+    fn serialize_seq<
+        T: Serialize<GatherTokens, ()>,
+        Iter: Iterator<T>
+    >(&mut self, mut iter: Iter) -> () {
+        let (len, _) = iter.size_hint();
+        self.serialize(SeqStart(len));
+        let mut first = false;
+        for elt in iter {
+            self.serialize_seq_elt(first, elt);
+
+            if first {
+                first = false;
+            }
+        }
+        self.serialize(End)
+    }
+
+    fn serialize_seq_elt<
+        T: Serialize<GatherTokens, ()>
+    >(&mut self, _first: bool, value: T) -> () {
+        value.serialize(self);
+    }
+
+    fn serialize_tuple<
+        V: Visitor<GatherTokens, ()>
+    >(&mut self, mut visitor: V) -> () {
+        let (len, _) = visitor.size_hint();
+        self.tokens.push(SeqStart(len));
+        loop {
+            match visitor.visit(self) {
+                Some(()) => { }
+                None => { break; }
+            }
+        }
+        self.tokens.push(End)
+    }
+
+    fn serialize_tuple_struct<
+        V: Visitor<GatherTokens, ()>
+    >(&mut self, _name: &'static str, visitor: V) -> () {
+        self.serialize_tuple(visitor)
+    }
+
+    fn serialize_enum<
+        V: Visitor<GatherTokens, ()>
+    >(&mut self, _name: &'static str, _variant: &'static str, visitor: V) -> () {
+        self.serialize_tuple(visitor)
+    }
+
+    fn serialize_map<
+        K: Serialize<GatherTokens, ()>,
+        V: Serialize<GatherTokens, ()>,
+        Iter: Iterator<(K, V)>
+    >(&mut self, mut iter: Iter) -> () {
+        let (len, _) = iter.size_hint();
+        self.serialize(MapStart(len));
+        let mut first = true;
+        for (key, value) in iter {
+            self.serialize_map_elt(first, key, value);
+            first = false;
+        }
+        self.serialize(End)
+    }
+
+    fn serialize_map_elt<
+        K: Serialize<GatherTokens, ()>,
+        V: Serialize<GatherTokens, ()>
+    >(&mut self, _first: bool, key: K, value: V) -> () {
+        key.serialize(self);
+        value.serialize(self);
+    }
+
+    fn serialize_struct<
+        V: Visitor<GatherTokens, ()>
+    >(&mut self, name: &'static str, mut visitor: V) -> () {
+        let (len, _) = visitor.size_hint();
+        self.serialize(StructStart(name, len));
+        loop {
+            match visitor.visit(self) {
+                Some(()) => { }
+                None => { break; }
+            }
+        }
+        self.serialize(End)
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+struct FormatState<W: Writer> {
+    writer: W,
+}
+
+impl<W: Writer> FormatState<W> {
+    fn new(writer: W) -> FormatState<W> {
+        FormatState {
+            writer: writer,
+        }
+    }
+}
+
+impl<W: Writer> SerializeState<IoResult<()>> for FormatState<W> {
+    fn serialize_int(&mut self, value: int) -> IoResult<()> {
+        write!(self.writer, "{}", value)
+    }
+
+    fn serialize_str(&mut self, value: &'static str) -> IoResult<()> {
+        write!(self.writer, "{}", value)
+    }
+
+    fn serialize_seq<
+        T: Serialize<FormatState<W>, IoResult<()>>,
+        Iter: Iterator<T>
+    >(&mut self, mut iter: Iter) -> IoResult<()> {
+        try!(write!(self.writer, "["));
+        let mut first = true;
+        for elt in iter {
+            try!(self.serialize_seq_elt(first, elt));
+            first = false;
+
+        }
+        write!(self.writer, "]")
+    }
+
+    fn serialize_seq_elt<
+        T: Serialize<FormatState<W>, IoResult<()>>
+    >(&mut self, first: bool, value: T) -> IoResult<()> {
+        if !first {
+            try!(write!(self.writer, ", "));
+        }
+
+        value.serialize(self)
+    }
+
+    fn serialize_tuple<
+        V: Visitor<FormatState<W>, IoResult<()>>
+    >(&mut self, mut visitor: V) -> IoResult<()> {
+        try!(write!(self.writer, "["));
+        loop {
+            match visitor.visit(self) {
+                Some(Ok(())) => { }
+                Some(Err(err)) => { return Err(err); }
+                None => { break; }
+            }
+        }
+        write!(self.writer, "]")
+    }
+
+    fn serialize_tuple_struct<
+        V: Visitor<FormatState<W>, IoResult<()>>
+    >(&mut self, _name: &'static str, visitor: V) -> IoResult<()> {
+        self.serialize_tuple(visitor)
+    }
+
+
+    fn serialize_enum<
+        V: Visitor<FormatState<W>, IoResult<()>>
+    >(&mut self, _name: &'static str, _variant: &'static str, visitor: V) -> IoResult<()> {
+        self.serialize_tuple(visitor)
+    }
+
+    fn serialize_map<
+        K: Serialize<FormatState<W>, IoResult<()>>,
+        V: Serialize<FormatState<W>, IoResult<()>>,
+        Iter: Iterator<(K, V)>
+    >(&mut self, mut iter: Iter) -> IoResult<()> {
+        try!(write!(self.writer, "{{"));
+        let mut first = true;
+        for (key, value) in iter {
+            try!(self.serialize_map_elt(first, &key, &value))
+            first = false;
+        }
+        write!(self.writer, "}}")
+    }
+
+    fn serialize_map_elt<
+        K: Serialize<FormatState<W>, IoResult<()>>,
+        V: Serialize<FormatState<W>, IoResult<()>>
+    >(&mut self, first: bool, key: K, value: V) -> IoResult<()> {
+        if !first {
+            try!(write!(self.writer, ", "));
+        }
+
+        try!(key.serialize(self));
+        try!(write!(self.writer, ": "));
+        value.serialize(self)
+    }
+
+    fn serialize_struct<
+        V: Visitor<FormatState<W>, IoResult<()>>
+    >(&mut self, _name: &'static str, mut visitor: V) -> IoResult<()> {
+        try!(write!(self.writer, "{{"));
+        loop {
+            match visitor.visit(self) {
+                Some(Ok(())) => { }
+                Some(Err(err)) => { return Err(err); }
+                None => { break; }
+            }
+        }
+        write!(self.writer, "}}")
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+#[deriving(PartialEq)]
+pub enum Json {
+    Integer(int),
+    String(String),
+    Array(Vec<Json>),
+    Object(TreeMap<String, Json>),
+}
+
+pub struct JsonSerializer {
+    key: Option<String>
+}
+
+impl JsonSerializer {
+    pub fn new() -> JsonSerializer {
+        JsonSerializer {
+            key: None
+        }
+    }
+}
+
+impl SerializeState<Json> for JsonSerializer {
+    fn serialize_int(&mut self, value: int) -> Json {
+        Integer(value)
+    }
+
+    fn serialize_str(&mut self, value: &'static str) -> Json {
+        String(value.to_string())
+    }
+
+    fn serialize_seq<
+        T: Serialize<JsonSerializer, Json>,
+        Iter: Iterator<T>
+    >(&mut self, mut iter: Iter) -> Json {
+        let (len, _) = iter.size_hint();
+        let mut v = Vec::with_capacity(len);
+
+        let mut first = true;
+        for elt in iter {
+            v.push(self.serialize_seq_elt(first, elt));
+            first = false;
+        }
+
+        Array(v)
+    }
+
+    fn serialize_seq_elt<
+        T: Serialize<JsonSerializer, Json>
+    >(&mut self, _first: bool, value: T) -> Json {
+        value.serialize(self)
+    }
+
+    fn serialize_tuple<
+        V: Visitor<JsonSerializer, Json>
+    >(&mut self, mut visitor: V) -> Json {
+        let (len, _) = visitor.size_hint();
+        let mut v = Vec::with_capacity(len);
+
+        loop {
+            match visitor.visit(self) {
+                Some(value) => { v.push(value); }
+                None => { break; }
+            }
+        }
+
+        Array(v)
+    }
+
+    fn serialize_tuple_struct<
+        V: Visitor<JsonSerializer, Json>
+    >(&mut self, _name: &'static str, visitor: V) -> Json {
+        self.serialize_tuple(visitor)
+    }
+
+    fn serialize_enum<
+        V: Visitor<JsonSerializer, Json>
+    >(&mut self, _name: &'static str, _variant: &'static str, visitor: V) -> Json {
+        self.serialize_tuple(visitor)
+    }
+
+    fn serialize_map<
+        K: Serialize<JsonSerializer, Json>,
+        V: Serialize<JsonSerializer, Json>,
+        Iter: Iterator<(K, V)>
+    >(&mut self, mut iter: Iter) -> Json {
+        let mut v = TreeMap::new();
+        let mut first = true;
+
+        for (key, value) in iter {
+            let value = self.serialize_map_elt(first, key, value);
+            v.insert(self.key.take().unwrap(), value);
+            first = false;
+        }
+
+        Object(v)
+    }
+
+    fn serialize_map_elt<
+        K: Serialize<JsonSerializer, Json>,
+        V: Serialize<JsonSerializer, Json>
+    >(&mut self, _first: bool, key: K, value: V) -> Json {
+        match key.serialize(self) {
+            String(key) => { self.key = Some(key); }
+            _ => { fail!() }
+        }
+        value.serialize(self)
+    }
+
+    fn serialize_struct<
+        V: Visitor<JsonSerializer, Json>
+    >(&mut self, _name: &'static str, mut visitor: V) -> Json {
+        let mut v = TreeMap::new();
+
+        loop {
+            match visitor.visit(self) {
+                Some(value) => { v.insert(self.key.take().unwrap(), value); }
+                None => { break; }
+            }
+        }
+
+        Object(v)
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+/*
+pub fn to_format_vec<
+    W: Writer,
+    T: Serialize<FormatState<W>, IoResult<()>>
+>(value: &T) -> IoResult<Vec<u8>> {
+    let mut writer = io::MemWriter::new();
+    {
+        let mut w = FormatState::new(writer.by_ref());
+        try!(value.serialize(&mut w));
+    }
+    Ok(writer.unwrap())
+}
+
+pub fn to_format_string<
+    T: Serialize<FormatState<io::MemWriter>, IoResult<()>>
+>(value: &T) -> IoResult<Result<String, Vec<u8>>> {
+    let vec = try!(to_format_vec(value));
+    Ok(String::from_utf8(vec))
+}
+*/
+
+///////////////////////////////////////////////////////////////////////////////
+
+struct Foo {
+    x: int,
+    y: int,
+    z: &'static str,
+}
+
+impl<S: SerializeState<R>, R> Serialize<S, R> for Foo {
+    fn serialize(&self, state: &mut S) -> R {
+        let mut x = FooSerialize {
+            value: self,
+            state: 0,
+            foo_state: state,
+        };
+        x.foo_state.serialize_struct("Foo", &mut x)
+        /*
+        state.serialize_struct("Foo", FooSerialize {
+            value: self,
+            state: 0,
+            foo_state: state,
+        })
+        */
+    }
+}
+
+struct FooSerialize<'a, S> {
+    value: &'a Foo,
+    state: uint,
+    foo_state: &'a mut S,
+}
+
+impl<'a, S: SerializeState<R>, R> Visitor<S, R> for FooSerialize<'a, S> {
+    fn visit(&mut self, state: &mut S) -> Option<R> {
+        match self.state {
+            0 => {
+                self.state += 1;
+                Some(state.serialize_map_elt(true, "x", &self.value.x))
+            }
+            1 => {
+                self.state += 1;
+                Some(state.serialize_map_elt(false, "y", &self.value.y))
+            }
+            2 => {
+                self.state += 1;
+                Some(state.serialize_map_elt(false, "z", &self.value.z))
+            }
+            _ => {
+                None
+            }
+        }
+    }
+
+    fn size_hint(&self) -> (uint, Option<uint>) {
+        let size = 3 - self.state;
+        (size, Some(size))
+    }
+}
+
+fn main() {
+
+    let value = 5i;
+
+    let mut s = GatherTokens::new();
+    value.serialize(&mut s);
+    println!("tokens: {}", s.unwrap());
+
+    value.serialize(&mut FormatState::new(io::stdout())).unwrap();
+    println!("");
+
+    ////
+
+    let value = vec!(1i, 2, 3);
+
+    let mut s = GatherTokens::new();
+    value.serialize(&mut s);
+    println!("tokens: {}", s.unwrap());
+
+    value.serialize(&mut FormatState::new(io::stdout())).unwrap();
+    println!("");
+
+    ////
+
+    let mut value = TreeMap::new();
+    value.insert("a", 1i);
+    value.insert("b", 2);
+    value.insert("c", 3);
+
+    let mut s = GatherTokens::new();
+    value.serialize(&mut s);
+    println!("tokens: {}", s.unwrap());
+
+    value.serialize(&mut FormatState::new(io::stdout())).unwrap();
+    println!("");
+
+    ////
+
+    /*
+    println!("{}", to_format_vec(&5i));
+    println!("{}", to_format_string(&5i));
+    */
+
+    let value = Foo { x: 1, y: 2, z: "abc" };
+
+    let mut s = GatherTokens::new();
+    value.serialize(&mut s);
+    println!("tokens: {}", s.unwrap());
+
+    value.serialize(&mut FormatState::new(io::stdout())).unwrap();
+    println!("");
+
+    ////
+
+    let value = (1i, "abc");
+
+    let mut s = GatherTokens::new();
+    value.serialize(&mut s);
+    println!("tokens: {}", s.unwrap());
+
+    value.serialize(&mut FormatState::new(io::stdout())).unwrap();
+    println!("");
+}