Flesh out the ast module in rustc a little.

src/comp/fe/ast.rs

@@ -1,4 +1,50 @@
-type crate = rec( str filename );
+
+import std.util.option;
+import std.map.hashmap;
+
+type ident = str;
+
+type crate = rec( str filename,
+                  _mod module);
+
+type block = vec[stmt];
+
+type stmt = tag( stmt_block(block),
+                 stmt_decl(@decl),
+                 stmt_ret(option[@lval]) );
+
+type decl = tag( decl_local(ident, option[ty]),
+                 decl_item(ident, @item) );
+
+type lval = tag( lval_ident(ident),
+                 lval_ext(@lval, ident),
+                 lval_idx(@lval, @atom) );
+
+type atom = tag( atom_lit(lit));
+
+type lit = tag( lit_char(char),
+                lit_int(int),
+                lit_nil(),
+                lit_bool(bool) );
+
+type ty = tag( ty_nil(),
+               ty_bool(),
+               ty_int(),
+               ty_char() );
+
+type mode = tag( local(), alias() );
+
+type slot = rec(ty ty, mode mode);
+
+type _fn = rec(vec[rec(slot slot, ident ident)] inputs,
+               slot output,
+               block body);
+
+type _mod = hashmap[ident,item];
+
+type item = tag( item_fn(@_fn),
+                 item_mod(@_mod) );
+
 
 //
 // Local Variables: