diff --git a/src/comp/metadata/astencode.rs b/src/comp/metadata/astencode.rs
new file mode 100644
index 0000000000000..002296a656dfe
--- /dev/null
+++ b/src/comp/metadata/astencode.rs
@@ -0,0 +1,653 @@
+// Encoding of ASTs and the associated side tables.
+
+import middle::base::trans::common::crate_ctxt;
+import syntax::ast;
+import syntax::codemap::{span, filename};
+import std::ebml::writer;
+import metadata::common::*;
+
+enum ast_tag {
+    at_span,
+    at_id,
+
+    at_span_expninfo_callie_name,
+    at_span_expninfo_callie_span,
+
+    at_blk,
+    at_blk_stmts,
+    at_blk_expr,
+    at_blk_rules,
+
+    at_stmt,
+    at_stmt_node_decl,
+    at_stmt_node_expr,
+
+    at_expr,
+    at_expr_node_vec,
+    at_expr_node_rec,
+    at_expr_node_call,
+    at_expr_node_tup,
+    at_expr_node_bind,
+    at_expr_node_bind_args,
+    at_expr_node_binary,
+    at_expr_node_unary,
+    at_expr_node_lit,
+    at_expr_node_cast,
+    at_expr_node_if,
+    at_expr_node_while,
+
+    at_none,
+    at_some,
+}
+
+type ast_ctxt = {
+    embl_w: ebml::writer,
+    ccx: crate_ctxt,
+};
+
+impl ast_output for ast_ctxt {
+    fn tag(tag: ast_tag, blk: fn()) {
+        self.embl_w.wr_tag(tag as uint, blk)
+    }
+
+    fn uint(v: uint) {
+        self.embl_w.wr_uint(v)
+    }
+
+    fn opt<T>(x: option<T>, blk: fn(T)) {
+        alt x {
+          none { self.tag(at_none) {||} }
+          some(v) { self.tag(at_some) {|| blk(v) } }
+        }
+    }
+
+    fn str(tag: ast_tag, v: str) {
+        self.tag(tag) {|| self.embl_w.wr_str(v) };
+    }
+
+    fn vec<T>(tag: ast_tag, v: [T], blk: fn(T)) {
+        self.tag(tag) {||
+            self.uint(vec::len(v));
+            vec::iter(v) {|e| blk(e) };
+        }
+    }
+
+    fn span(sp: span) {
+        self.tag(at_span) {||
+            self.uint(sp.lo);
+            self.uint(sp.hi);
+            self.opt(sp.expn_info) {|ei|
+                self.span(ei.call_site);
+                self.str(at_span_expninfo_callie_name, ei.callie.name);
+                self.opt(ei.callie.span) {|v| self.span(v) };
+            }
+        }
+    }
+
+    fn id(id: uint) {
+        self.tag(at_id) {|| self.uint(id); }
+    }
+
+    fn blk(blk: ast::blk) {
+        self.tag(at_blk) {||
+            self.id(blk.node.id);
+            self.span(blk.span);
+            self.vec(at_blk_stmts, blk.node.stmts) {|stmt|
+                self.stmt(stmt)
+            }
+            self.tag(at_blk_expr) {||
+                self.opt(blk.node.expr) {|e| self.expr(e) }
+            }
+            self.tag(at_blk_rules) {||
+                self.uint(blk.node.rules as uint);
+            }
+        }
+    }
+
+    fn decl(decl: ast::decl) {
+        self.span(decl.span);
+        alt decl.node {
+          ast::decl_local(lcls) {
+            self.vec(at_decl_local, lcls) {|lcl|
+                self.local(lcl)
+            }
+          }
+
+          ast::decl_item(item) {
+            self.tag(at_decl_item) {||
+                self.item(item);
+            }
+          }
+        }
+    }
+
+    fn local(lcl: ast::local) {
+        self.span(lcl.span);
+        self.ty(lcl.ty);
+        self.pat(lcl.pat);
+        self.opt(lcl.init) {|i| self.initializer(i) };
+        self.uint(lcl.id);
+    }
+
+    fn pat(pat: ast::pat) {
+        self.uint(pat.id);
+        self.span(pat.span);
+        alt pat_util::normalize_pat(pat.node) {
+          pat_wild {
+            self.tag(at_pat_wild) {||
+            }
+          }
+          pat_ident(path, o_pat) {
+            self.tag(at_pat_ident) {||
+                self.path(path);
+                self.opt(o_pat) {|p|
+                    self.pat(p)
+                }
+            }
+          }
+          pat_enum(path, pats) {
+            self.tag(at_pat_enum) {||
+                self.path(path);
+                self.vec(at_pat_enum_pats, pats) {|p| self.pat(p) };
+            }
+          }
+          pat_rec(field_pats, b) {
+            self.tag(at_pat_rec) {||
+                self.vec(at_pat_rec_fields, field_pats) {|p|
+                    self.field_pat(p)
+                }
+            }
+          }
+          pat_tup(pats) {
+            self.vec(at_pat_tup, pats) {|p| self.pat(p); }
+          }
+          pat_box(pat) {
+            self.tag(at_pat_box) {|| self.pat(pat) }
+          }
+          pat_lit(expr) {
+            self.tag(at_pat_lit) {|| self.expr(expr) }
+          }
+          pat_range(l, h) {
+            self.tag(at_pat_range) {||
+                self.expr(l);
+                self.expr(h);
+            }
+          }
+        }
+    }
+
+    fn stmt(stmt: ast::stmt) {
+        self.tag(at_stmt) {||
+            self.span(stmt.span);
+            alt stmt.node {
+              ast::stmt_decl(d, nid) {
+                self.id(nid);
+                self.tag(at_stmt_node_decl) {|| self.decl(d) };
+              }
+              ast::stmt_expr(e, nid) | ast::stmt_semi(e, nid) {
+                self.id(nid);
+                self.tag(at_stmt_node_expr) {|| self.expr(e) };
+              }
+            }
+        }
+    }
+
+    fn exprs(exprs: [ast::expr]) {
+        self.vec(at_exprs, exprs) {|e| self.expr(e) };
+    }
+
+    fn expr(expr: ast:expr) {
+        self.id(expr.id);
+        self.span(expr.span);
+        alt expr.node {
+          ast::expr_vec(subexprs, mutbl) {
+            self.tag(at_expr_node_vec) {||
+                self.exprs(subexprs);
+                self.mutbl(mutbl);
+            }
+          }
+
+          ast::expr_rec(fields, opt_expr) {
+            self.tag(at_expr_node_rec) {||
+                self.fields(fields);
+                self.opt(opt_expr) {|e| self.expr(e) };
+            }
+          }
+
+          ast::expr_call(func, args, _) {
+            self.tag(at_expr_node_call) {||
+                self.expr(func);
+                self.exprs(args);
+            }
+          }
+
+          ast::expr_tup(exprs) {
+            self.tag(at_expr_node_tup) {||
+                self.exprs(exprs);
+            }
+          }
+
+          ast::expr_bind(f, args) {
+            self.tag(at_expr_node_bind) {||
+                self.expr(f);
+                self.vec(at_expr_node_bind_args, args) {|opt_e|
+                    self.opt(opt_e) {|e| self.expr(e)};
+                }
+            }
+          }
+
+          ast::expr_binary(binop, l, r) {
+            self.tag(at_expr_node_binary) {||
+                self.uint(binop as uint);
+                self.expr(l);
+                self.expr(r);
+            }
+          }
+
+          ast::expr_unary(unop, l, r) {
+            self.tag(at_expr_node_unary) {||
+                self.uint(unop as uint);
+                self.expr(l);
+                self.expr(r);
+            }
+          }
+
+          ast::expr_lit(lit) {
+            self.tag(at_expr_node_lit) {|| self.lit(lit) }
+          }
+
+          ast::expr_cast(expr, ty) {
+            self.tag(at_expr_node_cast) {||
+                self.expr(expr);
+                self.ty(ty);
+            }
+          }
+
+          ast::expr_if(cond, blk_then, o_blk_else) {
+            self.tag(at_expr_node_if) {||
+                self.expr(cond);
+                self.blk(blk_then);
+                self.opt(o_blk_else) {|b| self.blk(b)};
+            }
+          }
+
+          ast::expr_while(cond, blk) {
+            self.tag(at_expr_node_while) {||
+                self.expr(cond);
+                self.blk(blk);
+            }
+          }
+
+          ast::expr_for(lcl, expr, blk) {
+            self.tag(at_expr_node_for) {||
+                self.local(lcl);
+                self.expr(expr);
+                self.blk(blk);
+            }
+          }
+
+          ast::expr_do_while(blk, cond) {
+            self.tag(at_expr_node_do_while) {||
+                self.blk(blk);
+                self.expr(cond);
+            }
+          }
+
+          ast::expr_alt(cond, arms) {
+            self.tag(at_expr_node_alt) {||
+                self.blk(blk);
+                self.expr(cond);
+            }
+          }
+
+          ast::expr_block(blk) {
+            self.tag(at_expr_node_blk) {||
+                self.blk(blk);
+            }
+          }
+
+          ast::expr_copy(expr) {
+            self.tag(at_expr_node_copy) {||
+                self.expr(expr);
+            }
+          }
+
+          ast::expr_move(l, r) {
+            self.tag(at_expr_node_move) {||
+                self.expr(l);
+                self.expr(r);
+            }
+          }
+
+          ast::expr_assign(l, r) {
+            self.tag(at_expr_node_assign) {||
+                self.expr(l);
+                self.expr(r);
+            }
+          }
+
+          ast::expr_swap(l, r) {
+            self.tag(at_expr_node_swap) {||
+                self.expr(l);
+                self.expr(r);
+            }
+          }
+
+          ast::expr_assign_of(binop, l, r) {
+            self.tag(at_expr_node_assign_op) {||
+                self.uint(binop as uint);
+                self.expr(l);
+                self.expr(r);
+            }
+          }
+
+          ast::expr_field(base, f, tys) {
+            self.tag(at_expr_node_field) {||
+                self.expr(base);
+                self.str(at_ident, f);
+                self.vec(at_tys) {|v| self.ty(v) }
+            }
+          }
+
+          ast::expr_index(l, r) {
+            self.tag(at_expr_node_index) {||
+                self.expr(l);
+                self.expr(r);
+            }
+          }
+
+          ast::expr_path(pth) {
+            self.tag(at_expr_node_path) {||
+            }
+          }
+
+          ast::expr_fail(o_expr) {
+            self.tag(at_expr_node_fail) {||
+                self.opt(o_expr) {|e| self.expr(e) }
+            }
+          }
+
+          ast::expr_break {
+            self.tag(at_expr_node_break) {||}
+          }
+
+          ast::expr_cont {
+            self.tag(at_expr_node_cont) {||}
+          }
+
+          ast::expr_ret(o_expr) {
+            self.tag(at_expr_node_ret) {||
+                self.opt(o_expr) {|e| self.expr(e) }
+            }
+          }
+
+          ast::expr_be(expr) {
+            self.tag(at_expr_node_be) {||
+                self.expr(expr)
+            }
+          }
+
+          ast::expr_log(i, e1, e2) {
+            self.tag(at_expr_node_log) {||
+                self.uint(i);
+                self.expr(e1);
+                self.expr(e2);
+            }
+          }
+
+          ast::expr_assert(e) {
+            self.tag(at_expr_node_assert) {||
+                self.expr(e);
+            }
+          }
+
+          ast::expr_check(mode, e) {
+            self.tag(at_expr_node_check) {||
+                self.uint(mode as uint);
+                self.expr(e);
+            }
+          }
+
+          ast::expr_if_check(cond, b, e) {
+            self.tag(at_expr_node_if_check) {||
+                self.expr(cond);
+                self.blk(b);
+                self.opt(e) {|e| self.blk(e)};
+            }
+          }
+
+          ast::expr_mac(m) {
+            self.tag(at_expr_node_mac) {||
+                /* todo */
+            }
+          }
+        }
+    }
+
+    fn lit(l: ast::lit) {
+        alt l {
+          lit_str(s) {
+            self.str(at_lit_str, s);
+          }
+          lit_int(i, t) {
+            self.tag(at_lit_int) {||
+                self.i64(i);
+                self.int_ty(t);
+            }
+          }
+          lit_uint(i, t) {
+            self.tag(at_lit_uint) {||
+                self.u64(i);
+                self.uint_ty(t);
+            }
+          }
+          lit_float(s, f) {
+            self.tag(at_lit_float) {||
+                self.str(at_value, s);
+                self.float_ty(f);
+            }
+          }
+          lit_nil {
+            self.tag(at_lit_nil) {||}
+          }
+          lit_bool(true) {
+            self.tag(at_lit_true) {||}
+          }
+          lit_bool(false) {
+            self.tag(at_lit_false) {||}
+          }
+        }
+    }
+
+    fn int_ty(t: ast::int_ty) {
+        self.uint(t as uint);
+    }
+
+    fn uint_ty(t: ast::uint_ty) {
+        self.uint(t as uint);
+    }
+
+    fn float_ty(t: ast::float_ty) {
+        self.uint(t as uint);
+    }
+
+    fn ty(ty: ast::ty) {
+        self.tag(at_ty) {||
+            self.span(ty.span);
+            alt ty.node {
+              ty_nil {
+                self.tag(at_ty_nil) {||}
+              }
+
+              ty_bot {
+                self.tag(at_ty_bot) {||}
+              }
+
+              ty_box({ty: ty, mut: m}) {
+                self.tag(at_ty_box) {||
+                    self.ty(ty);
+                    self.mutbl(m);
+                }
+              }
+
+              ty_uniq({ty: ty, mut: m}) {
+                self.tag(at_ty_uniq) {||
+                    self.ty(ty);
+                    self.mutbl(m);
+                }
+              }
+
+              ty_vec({ty: ty, mut: m}) {
+                self.tag(at_ty_vec) {||
+                    self.ty(ty);
+                    self.mutbl(m);
+                }
+              }
+
+              ty_ptr({ty: ty, mut: m}) {
+                self.tag(at_ty_ptr) {||
+                    self.ty(ty);
+                    self.mutbl(m);
+                }
+              }
+
+              ty_rec(fields) {
+                self.vec(at_ty_rec) {|f|
+                    self.field(f)
+                }
+              }
+
+              ty_fn(proto, fd) {
+                self.tag(at_ty_fn) {||
+                    self.uint(proto as uint);
+                    self.fn_decl(fd)
+                }
+              }
+
+              ty_tup(tys) {
+                self.vec(at_ty_tups) {|ty| self.ty(ty)}
+              }
+
+              ty_path(p, id) {
+                self.tag(at_ty_path) {||
+                    self.path(p);
+                    self.uint(id);
+                }
+              }
+
+              ty_constr(t, tcs) {
+                self.tag(at_ty_constr) {||
+                    self.ty(t);
+                    // ... constrs ... who cares ...
+                }
+              }
+
+              ty_mac(m) {
+                self.tag(at_ty_mac) {||
+                    self.mac(m);
+                };
+              }
+
+              ty_infer {
+                self.tag(at_ty_infer) {||
+                }
+              }
+            }
+        }
+    }
+
+    fn item(item: @ast::item) {
+        self.tag(at_item) {||
+            self.str(at_item_ident, item);
+            self.vec(at_item_attrs, item.attrs) {|a| self.attr(a)}
+            self.uint(item.id);
+            self.span(item.span);
+
+            alt item.node {
+              item_const(t, e) {
+                self.tag(at_item_const) {||
+                    self.ty(t);
+                    self.expr(e);
+                }
+              }
+              item_fn(d, tps, blk) {
+                self.tag(at_item_fn) {||
+                    self.fn_decl(d);
+                    self.ty_params(tps);
+                }
+              }
+              item_mod(m) {
+                self.tag(at_item_mod) {||
+                    self.mod_(m)
+                }
+              }
+              item_native_mod(nm) {
+                self.tag(at_item_native_mod) {||
+                    self.mod_(nm)
+                }
+              }
+              item_ty(ty, tps) {
+                self.tag(at_item_ty) {||
+                    self.ty(ty);
+                    self.ty_params(tps);
+                }
+              }
+              item_enum(variants, tps) {
+                self.tag(at_item_enum) {||
+                    self.ty(ty);
+                    self.ty_params(tps);
+                }
+              }
+              item_res(fd, tps, blk, node_id, node_id) {
+                self.tag(at_item_res) {||
+                    self.fn_decl(fd);
+                    self.ty_params(tps);
+                }
+              }
+              item_class(tps, citems, fn_decl, blk) {
+                self.tag(at_item_class) {||
+                    self.ty_params(tps);
+                    self.class_items(citems);
+                    self.fn_decl(fn_decl);
+                    self.blk(blk);
+                }
+              }
+              item_iface(tps, tms) {
+                self.tag(at_item_iface) {||
+                    self.ty_params(tps);
+                    self.ty_methods(tms);
+                }
+              }
+              item_impl(tps, iface_ty, self_ty, mthds) {
+                self.tag(at_item_impl) {||
+                    self.ty_params(tps);
+                    self.opt(iface_ty) {|t| self.ty(t) };
+                    self.ty(self_ty);
+                    self.methods(mthds);
+                }
+              }
+            }
+        }
+    }
+
+    fn ty_params(tps: [ast::ty_param]) {
+        self.vec(at_item_tps, tps) {|t| self.ty_param(t) }
+    }
+
+    fn ty_param(tp: ast::ty_param) {
+        self.str(at_ty_param_ident, tp.ident);
+        self.uint(at_ty_param_id, tp.id);
+        self.vec(at_param_bounds, *tp.bounds) {|b| self.ty_param_bound(b) };
+    }
+
+    fn ty_param_bound(b: ast::ty_param_bound) {
+        alt b {
+          bound_copy { self.tag(at_ty_param_bound_copy) {||} }
+          bound_send { self.tag(at_ty_param_bound_send) {||} }
+          bound_iface(t) {
+            self.tag(at_ty_param_bound_iface) {|| self.ty(t) }
+          }
+        }
+    }
+}
+
diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs
index 826ed0ea4bd8b..5c6e956508fc6 100644
--- a/src/comp/middle/ty.rs
+++ b/src/comp/middle/ty.rs
@@ -53,7 +53,7 @@ export sty;
 export substitute_type_params;
 export t;
 export new_ty_hash;
-export enum_variants;
+export enum_variants, substd_enum_variants;
 export iface_methods, store_iface_methods, impl_iface;
 export enum_variant_with_id;
 export ty_param_bounds_and_ty;
@@ -2357,6 +2357,20 @@ fn impl_iface(cx: ctxt, id: ast::def_id) -> option<t> {
 type variant_info = @{args: [t], ctor_ty: t, name: str,
                       id: ast::def_id, disr_val: int};
 
+fn substd_enum_variants(cx: ctxt, id: ast::def_id, tps: [ty::t])
+    -> [variant_info] {
+    vec::map(*enum_variants(cx, id)) { |variant_info|
+        let substd_args = vec::map(variant_info.args) {|aty|
+            substitute_type_params(cx, tps, aty)
+        };
+
+        let substd_ctor_ty =
+            substitute_type_params(cx, tps, variant_info.ctor_ty);
+
+        @{args: substd_args, ctor_ty: substd_ctor_ty with *variant_info}
+    }
+}
+
 fn enum_variants(cx: ctxt, id: ast::def_id) -> @[variant_info] {
     alt cx.enum_var_cache.find(id) {
       some(variants) { ret variants; }
diff --git a/src/serializer/serializer.rc b/src/serializer/serializer.rc
new file mode 100644
index 0000000000000..ba3a8467b9da0
--- /dev/null
+++ b/src/serializer/serializer.rc
@@ -0,0 +1,17 @@
+// -*- rust -*-
+
+// serializer --- Rust metadata encoder/decoder generator.
+//
+// This tool is not intended to generate usable modules (just yet),
+// though perhaps it will be beefed up.  But it can do a lot of the
+// grunt work for you.
+
+#[link(name = "serializer",
+       vers = "0.1",
+       uuid = "9ff87a04-8fed-4295-9ff8-f99bb802650b",
+       url = "http://rust-lang.org/doc/serializer")];
+
+#[crate_type = "bin"];
+
+use std;
+use rustc;
diff --git a/src/serializer/serializer.rs b/src/serializer/serializer.rs
new file mode 100644
index 0000000000000..f8c4349a7ce65
--- /dev/null
+++ b/src/serializer/serializer.rs
@@ -0,0 +1,294 @@
+import rustc::driver::{driver,session};
+import rustc::syntax::{ast, codemap};
+import rustc::syntax::parse::parser;
+import rustc::driver::diagnostic;
+import rustc::syntax::print::pprust;
+import rustc::syntax::codemap::span;
+import rustc::middle::ty;
+import rustc::middle::ast_map;
+import rustc::util::ppaux;
+import std::map::{hashmap, map, new_int_hash};
+import std::getopts;
+import std::io;
+import std::io::writer_util;
+import driver::build_session_options;
+import driver::build_session;
+import driver::build_configuration;
+
+type parse_result = {
+    crate: @ast::crate,
+    tcx: ty::ctxt,
+    roots: [str]
+};
+
+fn parse(argv: [str]) -> parse_result {
+    let argv = argv;
+    let argv0 = vec::shift(argv);
+    let match = result::get(getopts::getopts(argv, driver::opts()));
+    let sessopts = build_session_options(match, diagnostic::emit);
+    let sess = build_session(sessopts, "", diagnostic::emit);
+    let (ifile, roots) = {
+        let free = match.free;
+        if check vec::is_not_empty(free) {
+            let t = vec::tail(free);
+            (free[0], t)
+        } else {
+            fail "No input filename given.";
+        }
+    };
+    let cfg = build_configuration(sess, argv0, ifile);
+    alt driver::compile_upto(sess, cfg, ifile, driver::cu_typeck, none) {
+      {crate, tcx: some(tcx)} { {crate:crate, tcx:tcx, roots:roots} }
+      _ { fail "no type context"; }
+    }
+}
+
+type ast_expr = str;
+type ast_stmt = str;
+type ast_blk = str;
+type ast_pat = str;
+type ast_ty = str;
+type ast_item = str;
+
+type tp_map = map<ast::node_id, ty::t>;
+
+type serialize_ctx = {
+    crate: @ast::crate,
+    tcx: ty::ctxt,
+
+    tyfns: hashmap<ty::t, str>,
+    mutable item_fns: [ast_item],
+    mutable constants: [str]
+
+    // needed for #ast:
+    // opts: @{cfg: ast::crate_cfg},
+    // psess: parser::parse_sess
+};
+
+fn item_has_name(&&item: @ast::item, &&name: str) -> bool {
+    item.ident == name
+}
+
+fn lookup(_mod: ast::_mod, idx: uint, names: [str]) -> @ast::item {
+    let name = names[idx];
+    alt vec::find(_mod.items, bind item_has_name(_, name)) {
+      none { fail #fmt["cannot resolve name %s at index %u", name, idx]; }
+      some(item) if idx == vec::len(names) - 1u { item }
+      some(item) {
+        alt item.node {
+          ast::item_mod(_m) { lookup(_m, idx + 1u, names) }
+          _ { fail #fmt["name %s at index %u not a module", name, idx]; }
+        }
+      }
+    }
+}
+
+impl serialize_ctx for serialize_ctx {
+    // fn session() -> parser::parse_sess { self.psess }
+
+    fn add_item(item: ast_item) {
+        self.item_fns += [item];
+    }
+
+    fn mk_serialize_named_item_fn(name: str) -> str {
+        let names = str::split_str(name, "::");
+        let item = lookup(self.crate.node.module, 0u, names);
+        let def_id = {crate: ast::local_crate, node: item.id};
+        self.mk_serialize_item_fn(def_id, [])
+    }
+
+    fn tp_map(ty_params: [ast::ty_param], tps: [ty::t]) -> tp_map {
+        assert vec::len(tps) == vec::len(ty_params);
+        let tps_map = new_int_hash();
+        vec::iter2(ty_params, tps) {|tp_def,tp_val|
+            tps_map.insert(tp_def.id, tp_val);
+        }
+        ret tps_map;
+    }
+
+    fn path(mod_: [str], id: str) -> str {
+        str::connect(mod_ + [id], "::")
+    }
+
+    fn ident(mod_: [str], id: str) -> str {
+        str::connect(mod_ + [id], "_")
+    }
+
+    fn instantiate(id: ast::def_id, args: [ty::t]) -> ty::t {
+        let {bounds, ty} = ty::lookup_item_type(self.tcx, id);
+
+        // typeck should guarantee this
+        assert vec::len(*bounds) == vec::len(args);
+
+        ret if vec::len(args) == 0u {
+            ty
+        } else {
+            ty::substitute_type_params(self.tcx, args, ty)
+        };
+    }
+
+    fn mk_serialize_item_fn(id: ast::def_id,
+                            tps: [ty::t]) -> str {
+        let item_ty = self.instantiate(id, tps);
+        self.mk_serialize_ty_fn(item_ty)
+    }
+
+    fn blk(stmts: [ast_stmt]) -> ast_blk {
+        "{" + str::connect(stmts, ";") + "}"
+    }
+
+    fn blk_expr(stmts: [ast_stmt]) -> ast_expr {
+        self.blk(stmts)
+    }
+
+    // Generates a function to serialize the given type.
+    // Returns an AST fragment that names this function.
+    fn serialize_ty(ty0: ty::t, v: ast_expr) -> ast_expr {
+        let fname = self.mk_serialize_ty_fn(ty0);
+        #fmt["%s(cx, %s)", fname, v]
+    }
+
+    fn mk_serialize_ty_fn(ty0: ty::t) -> str {
+        // check for existing function
+        alt self.tyfns.find(ty0) {
+          some(name) { ret name; }
+          none { /* fallthrough */ }
+        }
+
+        // define the name and insert into the hashtable
+        // in case of recursive calls:
+        let id = self.tyfns.size();
+        let ty0_str = ppaux::ty_to_str(self.tcx, ty0);
+        let name = #fmt["serialize_%u /*%s*/", id, ty0_str];
+        self.tyfns.insert(ty0, name);
+        let v = "v";
+
+        let body_node = alt ty::get(ty0).struct {
+          ty::ty_nil | ty::ty_bot { "()" }
+          ty::ty_int(_) { #fmt["serialize_i64(cx, %s as i64)", v] }
+          ty::ty_uint(_) { #fmt["serialize_u64(cx, %s as u64)", v] }
+          ty::ty_float(_) { #fmt["serialize_float(cx, %s as float)", v] }
+          ty::ty_bool { #fmt["serialize_bool(cx, %s)", v] }
+          ty::ty_str { #fmt["serialize_str(cx, %s)", v] }
+          ty::ty_enum(def_id, tps) { self.serialize_enum(v, def_id, tps) }
+          ty::ty_box(mt) | ty::ty_uniq(mt) | ty::ty_ptr(mt) {
+            self.serialize_ty(mt.ty, #fmt["*%s", v])
+          }
+          ty::ty_vec(mt) {
+            let selem = self.serialize_ty(mt.ty, "i");
+            #fmt["start_vec(cx); \
+                  vec::iter(v) {|i| \
+                  start_vec_item(cx); \
+                  %s; \
+                  end_vec_item(cx); \
+                  } \
+                  end_vec(cx);", selem]
+          }
+          ty::ty_rec(fields) {
+            let stmts = vec::map(fields) {|field|
+                let f_name = field.ident;
+                let f_ty = field.mt.ty;
+                self.serialize_ty(f_ty, #fmt["%s.%s", v, f_name])
+            };
+            self.blk_expr(stmts)
+          }
+          ty::ty_tup(tys) {
+            let (pat, stmts) = self.serialize_arm("", tys);
+            #fmt["alt %s { \
+                    %s %s \
+                  }", v, pat, self.blk_expr(stmts)]
+          }
+          ty::ty_constr(t, _) {
+            self.serialize_ty(t, v)
+          }
+          ty::ty_fn(_) |
+          ty::ty_iface(_, _) |
+          ty::ty_res(_, _, _) |
+          ty::ty_var(_) | ty::ty_param(_, _) |
+          ty::ty_self(_) | ty::ty_type | ty::ty_send_type |
+          ty::ty_opaque_closure_ptr(_) | ty::ty_opaque_box {
+            fail #fmt["Unhandled type %s", ty0_str]
+          }
+        };
+
+        let item = #fmt["fn %s(cx: ctxt, v: %s) {\
+                             %s;\
+                         }", name, ty0_str, body_node];
+        self.add_item(item);
+        ret name;
+    }
+
+    fn serialize_enum(v: ast_expr,
+                      id: ast::def_id,
+                      tps: [ty::t]) -> ast_expr {
+        let path = [];
+        let variants = ty::substd_enum_variants(self.tcx, id, tps);
+
+        let arms = vec::map(variants) {|variant|
+            let v_path = self.path(path, variant.name);
+            let n_args = vec::len(variant.args);
+            let (v_pat, stmts) = {
+                if n_args == 0u {
+                    (v_path, [])
+                } else {
+                    self.serialize_arm(v_path, variant.args)
+                }
+            };
+
+            let v_const = #fmt["at_%s", self.ident(path, variant.name)];
+
+            #fmt["%s { \
+                    start_variant(cx, %s); \
+                    %s \
+                    end_variant(cx, %s); \
+                  }", v_pat, v_const, self.blk(stmts), v_const]
+        };
+
+        #fmt["alt %s { \
+                %s \
+              }", v, str::connect(arms, "\n")]
+    }
+
+    fn serialize_arm(v_path: str, args: [ty::t]) -> (ast_pat, [ast_stmt]) {
+        let n_args = vec::len(args);
+        let arg_nms = vec::init_fn(n_args) {|i| #fmt["v%u", i] };
+        let v_pat =
+            #fmt["%s(%s)", v_path, str::connect(arg_nms, ", ")];
+        let stmts = vec::init_fn(n_args) {|i|
+            let arg_ty = args[i];
+            let serialize_expr =
+                self.serialize_ty(arg_ty, arg_nms[i]);
+            #fmt["%s;", serialize_expr]
+        };
+        (v_pat, stmts)
+    }
+}
+
+fn main(argv: [str]) {
+    let {crate, tcx, roots} = parse(argv);
+    let sctx: serialize_ctx = {
+        // let cm = codemap::new_codemap();
+        // let handler = diagnostic::mk_handler(option::none);
+        // let psess: parser::parse_sess = @{
+        //     cm: cm,
+        //     mutable next_id: 1,
+        //     span_diagnostic: diagnostic::mk_span_handler(handler, cm),
+        //     mutable chpos: 0u,
+        //     mutable byte_pos: 0u
+        // };
+        {crate: crate,
+         tcx: tcx,
+         tyfns: ty::new_ty_hash::<str>(),
+         mutable item_fns: [],
+         mutable constants: []}
+    };
+
+    vec::iter(roots) {|root|
+        sctx.mk_serialize_named_item_fn(root);
+    }
+
+    let stdout = io::stdout();
+    vec::iter(copy sctx.item_fns) {|item|
+        stdout.write_str(#fmt["%s\n", item])
+    }
+}
\ No newline at end of file
diff --git a/src/serializer/stest.rs b/src/serializer/stest.rs
new file mode 100644
index 0000000000000..c7161e07a2756
--- /dev/null
+++ b/src/serializer/stest.rs
@@ -0,0 +1,31 @@
+// Testing types for the serializer.  This should be made more formal.
+
+enum test1 {
+    t1_a(int), t1_b(str)
+}
+
+type test2 = {
+    f: int, g: str
+};
+
+enum test3 {
+    t3_a, t3_b
+}
+
+enum test4 {
+    t4_a(test1), t4_b(test2), t4_c(@test2), t4_d(@test4)
+}
+
+type spanned<A> = {
+    node: A,
+    span: { lo: uint, hi: uint }
+};
+
+type test5 = {
+    s1: spanned<test4>,
+    s2: spanned<uint>
+};
+
+type test6 = option<int>;
+
+fn main() {}
\ No newline at end of file