Difference between manually threading state and boxed closures in a piece of code using a parser-combinator.

http_parser.rs.diff

diff --git a/examples/http_parser.rs b/examples/http_parser.rs
index 5c31b35..196763e 100644
--- a/examples/http_parser.rs
+++ b/examples/http_parser.rs
@@ -41,17 +41,17 @@ fn is_not_space(c: u8)        -> bool { c != b' ' }
 fn is_end_of_line(c: u8)      -> bool { c == b'\r' || c == b'\n' }
 fn is_http_version(c: u8)     -> bool { c >= b'0' && c <= b'9' || c == b'.' }
 
-fn end_of_line<'a>(p: Empty<'a, u8>) -> Parser<'a, u8, u8, Error<u8>> {
-    or(mdo!{p,
+fn end_of_line<'a>() -> Parser<'a, 'a, u8, u8, Error<u8>> {
+    or(mdo!{
         char(b'\r');
         char(b'\n');
 
         ret u8, Error<u8>: b'\r'
-    }, |p| char(p, b'\n'))
+    }, char(b'\n'))
 }
 
-fn http_version<'a>(p: Empty<'a, u8>) -> Parser<'a, u8, &'a [u8], Error<u8>> {
-    mdo!{p,
+fn http_version<'a>() -> Parser<'a, 'a, u8, &'a [u8], Error<u8>> {
+    mdo!{
                       string(b"HTTP/");
         let version = take_while1(is_http_version);
 
@@ -59,13 +59,13 @@ fn http_version<'a>(p: Empty<'a, u8>) -> Parser<'a, u8, &'a [u8], Error<u8>> {
     }
 }
 
-fn request_line<'a>(p: Empty<'a, u8>) -> Parser<'a, u8, Request<'a>, Error<u8>> {
-    mdo!{p,
+fn request_line<'a>() -> Parser<'a, 'a, u8, Request<'a>, Error<u8>> {
+    mdo!{
         let method  = take_while1(is_token);
                       take_while1(is_space);
         let uri     = take_while1(is_not_space);
                       take_while1(is_space);
-        let version = http_version;
+        let version = http_version();
 
         ret Request {
             method:  method,
@@ -75,18 +75,18 @@ fn request_line<'a>(p: Empty<'a, u8>) -> Parser<'a, u8, Request<'a>, Error<u8>>
     }
 }
 
-fn message_header_line<'a>(p: Empty<'a, u8>) -> Parser<'a, u8, &'a [u8], Error<u8>> {
-    mdo!{p,
-                   take_while1(is_horizontal_space);
+fn message_header_line<'a>() -> Parser<'a, 'a, u8, &'a [u8], Error<u8>> {
+    mdo!{
+               take_while1(is_horizontal_space);
         let line = take_till(is_end_of_line);
-                   end_of_line;
+               end_of_line();
 
         ret line
     }
 }
 
-fn message_header<'a>(p: Empty<'a, u8>) -> Parser<'a, u8, Header, Error<u8>> {
-    mdo!{p,
+fn message_header<'a>() -> Parser<'a, 'a, u8, Header<'a>, Error<u8>> {
+    mdo!{
         let name  = take_while1(is_token);
                     char(b':');
         let lines = many1(message_header_line);
@@ -98,12 +98,12 @@ fn message_header<'a>(p: Empty<'a, u8>) -> Parser<'a, u8, Header, Error<u8>> {
     }
 }
 
-fn request<'a>(p: Empty<'a, u8>) -> Parser<'a, u8, (Request, Vec<Header>), Error<u8>> {
-    mdo!{p,
-        let r = request_line;
-                end_of_line;
+fn request<'a>() -> Parser<'a, 'a, u8, (Request<'a>, Vec<Header<'a>>), Error<u8>> {
+    mdo!{
+        let r = request_line();
+                end_of_line();
         let h = many(message_header);
-                end_of_line;
+                end_of_line();
 
         ret (r, h)
     }