diff --git a/Cargo.toml b/Cargo.toml
index 72b93ed..ca7635a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "chrono"
-version = "0.1.12"
+version = "0.1.13"
 authors = ["Kang Seonghoon <public+rust@mearie.org>"]
 
 description = "Date and time library for Rust"
@@ -15,5 +15,5 @@ license = "MIT/Apache-2.0"
 name = "chrono"
 
 [dependencies]
-time = "0.1.11"
+time = "0.1.12"
 
diff --git a/README.md b/README.md
index 4f448a8..b5408d7 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-[Chrono][doc] 0.1.12
+[Chrono][doc] 0.1.13
 ====================
 
 [![Chrono on Travis CI][travis-image]][travis]
@@ -115,17 +115,18 @@ assert_eq!(UTC.ymd(1970, 1, 1).and_hms(0, 0, 0) - Duration::seconds(1_000_000_00
 
 Formatting is done via the `format` method,
 which format is equivalent to the familiar `strftime` format.
-The default `to_string` method also gives a reasonable representation.
+The default `to_string` method and `{:?}` specifier also give a reasonable representation.
 
 ~~~~ {.rust}
 use chrono::{UTC, Offset};
 
 let dt = UTC.ymd(2014, 11, 28).and_hms(12, 0, 9);
-assert_eq!(dt.format("%Y-%m-%d %H:%M:%S").to_string(), "2014-11-28 12:00:09".to_string());
-assert_eq!(dt.format("%a %b %e %T %Y").to_string(), "Fri Nov 28 12:00:09 2014".to_string());
+assert_eq!(dt.format("%Y-%m-%d %H:%M:%S").to_string(), "2014-11-28 12:00:09");
+assert_eq!(dt.format("%a %b %e %T %Y").to_string(), "Fri Nov 28 12:00:09 2014");
 assert_eq!(dt.format("%a %b %e %T %Y").to_string(), dt.format("%c").to_string());
 
-assert_eq!(dt.to_string(), "2014-11-28T12:00:09Z".to_string());
+assert_eq!(dt.to_string(), "2014-11-28 12:00:09 UTC");
+assert_eq!(format!("{:?}", dt), "2014-11-28T12:00:09Z");
 ~~~~
 
 ### Individual date and time
@@ -143,7 +144,7 @@ assert_eq!(Local::today(), Local::now().date());
 
 assert_eq!(UTC.ymd(2014, 11, 28).weekday(), Weekday::Fri);
 assert_eq!(UTC.ymd_opt(2014, 11, 31), LocalResult::None);
-assert_eq!(UTC.hms_milli(7, 8, 9, 10).format("%H%M%S").to_string(), "070809".to_string());
+assert_eq!(UTC.hms_milli(7, 8, 9, 10).format("%H%M%S").to_string(), "070809");
 ~~~~
 
 `DateTime` has two methods, `date` and `time`,
diff --git a/src/date.rs b/src/date.rs
index d409f0e..5b0c556 100644
--- a/src/date.rs
+++ b/src/date.rs
@@ -175,17 +175,19 @@ impl<Off:Offset> Date<Off> {
         Date::from_utc(self.date, offset)
     }
 
+    /// Returns a view to the local date.
+    fn local(&self) -> NaiveDate {
+        self.offset.to_local_date(&self.date)
+    }
+}
+
+impl<Off: Offset + fmt::String> Date<Off> {
     /// Formats the date in the specified format string.
     /// See the `format` module on the supported escape sequences.
     #[inline]
     pub fn format<'a>(&'a self, fmt: &'a str) -> DelayedFormat<'a> {
         DelayedFormat::new_with_offset(Some(self.local()), None, &self.offset, fmt)
     }
-
-    /// Returns a view to the local date.
-    fn local(&self) -> NaiveDate {
-        self.offset.to_local_date(&self.date)
-    }
 }
 
 impl<Off:Offset> Datelike for Date<Off> {
@@ -259,8 +261,8 @@ impl<Off:Offset> Ord for Date<Off> {
     fn cmp(&self, other: &Date<Off>) -> Ordering { self.date.cmp(&other.date) }
 }
 
-impl<Off:Offset> hash::Hash for Date<Off> {
-    fn hash(&self, state: &mut hash::sip::SipState) { self.date.hash(state) }
+impl<Off: Offset, H: hash::Hasher + hash::Writer> hash::Hash<H> for Date<Off> {
+    fn hash(&self, state: &mut H) { self.date.hash(state) }
 }
 
 impl<Off:Offset> Add<Duration> for Date<Off> {
@@ -284,7 +286,13 @@ impl<Off:Offset> Sub<Duration> for Date<Off> {
     fn sub(self, rhs: Duration) -> Date<Off> { self.add(-rhs) }
 }
 
-impl<Off:Offset> fmt::Show for Date<Off> {
+impl<Off: Offset> fmt::Show for Date<Off> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{:?}{:?}", self.local(), self.offset)
+    }
+}
+
+impl<Off: Offset + fmt::String> fmt::String for Date<Off> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{}{}", self.local(), self.offset)
     }
@@ -292,9 +300,7 @@ impl<Off:Offset> fmt::Show for Date<Off> {
 
 #[cfg(test)]
 mod tests {
-    use std::borrow::IntoCow;
     use std::fmt;
-    use std::string::CowString;
 
     use duration::Duration;
     use naive::date::NaiveDate;
@@ -309,7 +315,6 @@ mod tests {
     struct UTC1y; // same to UTC but with an offset of 365 days
 
     impl Offset for UTC1y {
-        fn name(&self) -> CowString<'static> { "UTC+8760".into_cow() } // yes, no kidding
         fn local_minus_utc(&self) -> Duration { Duration::zero() }
 
         fn from_local_date(&self, local: &NaiveDate) -> LocalResult<Date<UTC1y>> {
@@ -335,13 +340,13 @@ mod tests {
 
     #[test]
     fn test_date_weird_offset() {
-        assert_eq!(UTC1y.ymd(2012, 2, 29).to_string(),
+        assert_eq!(format!("{:?}", UTC1y.ymd(2012, 2, 29)),
                    "2012-02-29+8760:00".to_string());
-        assert_eq!(UTC1y.ymd(2012, 2, 29).and_hms(5, 6, 7).to_string(),
+        assert_eq!(format!("{:?}", UTC1y.ymd(2012, 2, 29).and_hms(5, 6, 7)),
                    "2012-02-29T05:06:07+8760:00".to_string());
-        assert_eq!(UTC1y.ymd(2012, 3, 4).to_string(),
+        assert_eq!(format!("{:?}", UTC1y.ymd(2012, 3, 4)),
                    "2012-03-04+8760:00".to_string());
-        assert_eq!(UTC1y.ymd(2012, 3, 4).and_hms(5, 6, 7).to_string(),
+        assert_eq!(format!("{:?}", UTC1y.ymd(2012, 3, 4).and_hms(5, 6, 7)),
                    "2012-03-04T05:06:07+8760:00".to_string());
     }
 }
diff --git a/src/datetime.rs b/src/datetime.rs
index 39fe12e..b2341f2 100644
--- a/src/datetime.rs
+++ b/src/datetime.rs
@@ -64,6 +64,13 @@ impl<Off:Offset> DateTime<Off> {
         DateTime::from_utc(self.datetime, offset)
     }
 
+    /// Returns a view to the local datetime.
+    fn local(&self) -> NaiveDateTime {
+        self.offset.to_local_datetime(&self.datetime)
+    }
+}
+
+impl<Off: Offset + fmt::String> DateTime<Off> {
     /// Formats the combined date and time in the specified format string.
     /// See the `format` module on the supported escape sequences.
     #[inline]
@@ -71,11 +78,6 @@ impl<Off:Offset> DateTime<Off> {
         let local = self.local();
         DelayedFormat::new_with_offset(Some(local.date()), Some(local.time()), &self.offset, fmt)
     }
-
-    /// Returns a view to the local datetime.
-    fn local(&self) -> NaiveDateTime {
-        self.offset.to_local_datetime(&self.datetime)
-    }
 }
 
 impl<Off:Offset> Datelike for DateTime<Off> {
@@ -180,8 +182,8 @@ impl<Off:Offset> Ord for DateTime<Off> {
     fn cmp(&self, other: &DateTime<Off>) -> Ordering { self.datetime.cmp(&other.datetime) }
 }
 
-impl<Off:Offset> hash::Hash for DateTime<Off> {
-    fn hash(&self, state: &mut hash::sip::SipState) { self.datetime.hash(state) }
+impl<Off: Offset, H: hash::Hasher + hash::Writer> hash::Hash<H> for DateTime<Off> {
+    fn hash(&self, state: &mut H) { self.datetime.hash(state) }
 }
 
 impl<Off:Offset> Add<Duration> for DateTime<Off> {
@@ -205,9 +207,15 @@ impl<Off:Offset> Sub<Duration> for DateTime<Off> {
     fn sub(self, rhs: Duration) -> DateTime<Off> { self.add(-rhs) }
 }
 
-impl<Off:Offset> fmt::Show for DateTime<Off> {
+impl<Off: Offset> fmt::Show for DateTime<Off> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}{}", self.local(), self.offset)
+        write!(f, "{:?}{:?}", self.local(), self.offset)
+    }
+}
+
+impl<Off: Offset + fmt::String> fmt::String for DateTime<Off> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{} {}", self.local(), self.offset)
     }
 }
 
@@ -222,10 +230,15 @@ mod tests {
         let EST = FixedOffset::east(5*60*60);
         let EDT = FixedOffset::east(4*60*60);
 
-        assert_eq!(UTC.ymd(2014, 5, 6).and_hms(7, 8, 9).to_string(),
-                   "2014-05-06T07:08:09Z".to_string());
-        assert_eq!(EDT.ymd(2014, 5, 6).and_hms(7, 8, 9).to_string(),
-                   "2014-05-06T07:08:09+04:00".to_string());
+        assert_eq!(format!("{}", UTC.ymd(2014, 5, 6).and_hms(7, 8, 9)),
+                   "2014-05-06 07:08:09 UTC");
+        assert_eq!(format!("{}", EDT.ymd(2014, 5, 6).and_hms(7, 8, 9)),
+                   "2014-05-06 07:08:09 +04:00");
+        assert_eq!(format!("{:?}", UTC.ymd(2014, 5, 6).and_hms(7, 8, 9)),
+                   "2014-05-06T07:08:09Z");
+        assert_eq!(format!("{:?}", EDT.ymd(2014, 5, 6).and_hms(7, 8, 9)),
+                   "2014-05-06T07:08:09+04:00");
+
         assert_eq!(UTC.ymd(2014, 5, 6).and_hms(7, 8, 9), EDT.ymd(2014, 5, 6).and_hms(11, 8, 9));
         assert_eq!(UTC.ymd(2014, 5, 6).and_hms(7, 8, 9) + Duration::seconds(3600 + 60 + 1),
                    UTC.ymd(2014, 5, 6).and_hms(8, 9, 10));
diff --git a/src/div.rs b/src/div.rs
index cc5d600..750714f 100644
--- a/src/div.rs
+++ b/src/div.rs
@@ -43,28 +43,28 @@ mod tests {
 
     #[test]
     fn test_mod_floor() {
-        assert_eq!(mod_floor( 8i,  3),  2);
-        assert_eq!(mod_floor( 8i, -3), -1);
-        assert_eq!(mod_floor(-8i,  3),  1);
-        assert_eq!(mod_floor(-8i, -3), -2);
+        assert_eq!(mod_floor( 8,  3),  2);
+        assert_eq!(mod_floor( 8, -3), -1);
+        assert_eq!(mod_floor(-8,  3),  1);
+        assert_eq!(mod_floor(-8, -3), -2);
 
-        assert_eq!(mod_floor( 1i,  2),  1);
-        assert_eq!(mod_floor( 1i, -2), -1);
-        assert_eq!(mod_floor(-1i,  2),  1);
-        assert_eq!(mod_floor(-1i, -2), -1);
+        assert_eq!(mod_floor( 1,  2),  1);
+        assert_eq!(mod_floor( 1, -2), -1);
+        assert_eq!(mod_floor(-1,  2),  1);
+        assert_eq!(mod_floor(-1, -2), -1);
     }
 
     #[test]
     fn test_div_mod_floor() {
-        assert_eq!(div_mod_floor( 8i,  3), ( 2,  2));
-        assert_eq!(div_mod_floor( 8i, -3), (-3, -1));
-        assert_eq!(div_mod_floor(-8i,  3), (-3,  1));
-        assert_eq!(div_mod_floor(-8i, -3), ( 2, -2));
+        assert_eq!(div_mod_floor( 8,  3), ( 2,  2));
+        assert_eq!(div_mod_floor( 8, -3), (-3, -1));
+        assert_eq!(div_mod_floor(-8,  3), (-3,  1));
+        assert_eq!(div_mod_floor(-8, -3), ( 2, -2));
 
-        assert_eq!(div_mod_floor( 1i,  2), ( 0,  1));
-        assert_eq!(div_mod_floor( 1i, -2), (-1, -1));
-        assert_eq!(div_mod_floor(-1i,  2), (-1,  1));
-        assert_eq!(div_mod_floor(-1i, -2), ( 0, -1));
+        assert_eq!(div_mod_floor( 1,  2), ( 0,  1));
+        assert_eq!(div_mod_floor( 1, -2), (-1, -1));
+        assert_eq!(div_mod_floor(-1,  2), (-1,  1));
+        assert_eq!(div_mod_floor(-1, -2), ( 0, -1));
     }
 }
 
diff --git a/src/format.rs b/src/format.rs
index 439dd69..af7dc61 100644
--- a/src/format.rs
+++ b/src/format.rs
@@ -7,7 +7,6 @@
  */
 
 use std::fmt;
-use std::string::CowString;
 
 use {Datelike, Timelike};
 use duration::Duration;
@@ -17,7 +16,7 @@ use naive::time::NaiveTime;
 
 /// The internal workhouse for `DelayedFormat`.
 fn format(w: &mut fmt::Formatter, date: Option<&NaiveDate>, time: Option<&NaiveTime>,
-          off: Option<&(CowString<'static>, Duration)>, fmt: &str) -> fmt::Result {
+          off: Option<&(String, Duration)>, fmt: &str) -> fmt::Result {
     static SHORT_MONTHS: [&'static str; 12] =
         ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
     static LONG_MONTHS: [&'static str; 12] =
@@ -57,9 +56,9 @@ fn format(w: &mut fmt::Formatter, date: Option<&NaiveDate>, time: Option<&NaiveT
             // month
             (Some('m'), Some(d), _, _) => try!(write!(w, "{:02}", d.month())),
             (Some('b'), Some(d), _, _) | (Some('h'), Some(d), _, _) =>
-                try!(write!(w, "{}", SHORT_MONTHS[d.month0() as uint])),
+                try!(write!(w, "{}", SHORT_MONTHS[d.month0() as usize])),
             (Some('B'), Some(d), _, _) =>
-                try!(write!(w, "{}", LONG_MONTHS[d.month0() as uint])),
+                try!(write!(w, "{}", LONG_MONTHS[d.month0() as usize])),
 
             // day of month
             (Some('d'), Some(d), _, _) => try!(write!(w, "{:02}", d.day())),
@@ -76,9 +75,9 @@ fn format(w: &mut fmt::Formatter, date: Option<&NaiveDate>, time: Option<&NaiveT
 
             // day of week
             (Some('a'), Some(d), _, _) =>
-                try!(write!(w, "{}", SHORT_WEEKDAYS[d.weekday().num_days_from_monday() as uint])),
+                try!(write!(w, "{}", SHORT_WEEKDAYS[d.weekday().num_days_from_monday() as usize])),
             (Some('A'), Some(d), _, _) =>
-                try!(write!(w, "{}", LONG_WEEKDAYS[d.weekday().num_days_from_monday() as uint])),
+                try!(write!(w, "{}", LONG_WEEKDAYS[d.weekday().num_days_from_monday() as usize])),
             (Some('w'), Some(d), _, _) => try!(write!(w, "{}", d.weekday().num_days_from_sunday())),
             (Some('u'), Some(d), _, _) => try!(write!(w, "{}", d.weekday().number_from_monday())),
 
@@ -91,7 +90,7 @@ fn format(w: &mut fmt::Formatter, date: Option<&NaiveDate>, time: Option<&NaiveT
             (Some('F'), Some(d), _, _) => // `%Y-%m-%d'
                 try!(write!(w, "{:04}-{:02}-{:02}", d.year(), d.month(), d.day())),
             (Some('v'), Some(d), _, _) => // `%e-%b-%Y'
-                try!(write!(w, "{:2}-{}-{:04}", d.day(), SHORT_MONTHS[d.month0() as uint],
+                try!(write!(w, "{:2}-{}-{:04}", d.day(), SHORT_MONTHS[d.month0() as usize],
                                                 d.year())),
 
             // hour
@@ -141,8 +140,8 @@ fn format(w: &mut fmt::Formatter, date: Option<&NaiveDate>, time: Option<&NaiveT
             // combined date and time
             (Some('c'), Some(d), Some(t), _) => // `%a %b %e %T %Y`
                 try!(write!(w, "{} {} {:2} {:02}:{:02}:{:02} {:04}",
-                               SHORT_WEEKDAYS[d.weekday().num_days_from_monday() as uint],
-                               SHORT_MONTHS[d.month0() as uint], d.day(),
+                               SHORT_WEEKDAYS[d.weekday().num_days_from_monday() as usize],
+                               SHORT_MONTHS[d.month0() as usize], d.day(),
                                t.hour(), t.minute(), t.second(), d.year())),
             (Some('+'), Some(d), Some(t),
                         Some(&(_, ref local_minus_utc))) => { // `%Y-%m-%dT%H:%M:%S` plus tz
@@ -180,13 +179,14 @@ fn format(w: &mut fmt::Formatter, date: Option<&NaiveDate>, time: Option<&NaiveT
 
 /// A *temporary* object which can be used as an argument to `format!` or others.
 /// This is normally constructed via `format` methods of each date and time type.
+#[derive(Show)]
 pub struct DelayedFormat<'a> {
     /// The date view, if any.
     date: Option<NaiveDate>,
     /// The time view, if any.
     time: Option<NaiveTime>,
     /// The name and local-to-UTC difference for the offset (timezone), if any.
-    off: Option<(CowString<'static>, Duration)>,
+    off: Option<(String, Duration)>,
     /// The format string.
     fmt: &'a str,
 }
@@ -199,14 +199,15 @@ impl<'a> DelayedFormat<'a> {
     }
 
     /// Makes a new `DelayedFormat` value out of local date and time and UTC offset.
-    pub fn new_with_offset<Off:Offset>(date: Option<NaiveDate>, time: Option<NaiveTime>,
-                                       offset: &Off, fmt: &'a str) -> DelayedFormat<'a> {
-        let name_and_diff = (offset.name(), offset.local_minus_utc());
+    pub fn new_with_offset<Off>(date: Option<NaiveDate>, time: Option<NaiveTime>,
+                                offset: &Off, fmt: &'a str) -> DelayedFormat<'a>
+            where Off: Offset + fmt::String {
+        let name_and_diff = (offset.to_string(), offset.local_minus_utc());
         DelayedFormat { date: date, time: time, off: Some(name_and_diff), fmt: fmt }
     }
 }
 
-impl<'a> fmt::Show for DelayedFormat<'a> {
+impl<'a> fmt::String for DelayedFormat<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let ret = format(f, self.date.as_ref(), self.time.as_ref(), self.off.as_ref(), self.fmt);
         ret.map_err(|_| fmt::Error) // we don't have any good means to pass detailed errors...
diff --git a/src/lib.rs b/src/lib.rs
index 845a9d9..dc62965 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,7 +4,7 @@
 
 /*!
 
-# Chrono 0.1.12
+# Chrono 0.1.13
 
 Date and time handling for Rust. (also known as `rust-chrono`)
 It aims to be a feature-complete superset of the [time](https://github.com/rust-lang/time) library.
@@ -78,6 +78,7 @@ Addition and subtraction is also supported.
 The following illustrates most supported operations to the date and time:
 
 ~~~~ {.rust}
+# #![allow(unstable)]
 # /* we intentionally fake the datetime...
 use chrono::{UTC, Local, Datelike, Timelike, Weekday, Duration};
 
@@ -116,17 +117,19 @@ assert_eq!(UTC.ymd(1970, 1, 1).and_hms(0, 0, 0) - Duration::seconds(1_000_000_00
 
 Formatting is done via the `format` method,
 which format is equivalent to the familiar `strftime` format.
-The default `to_string` method also gives a reasonable representation.
+The default `to_string` method and `{:?}` specifier also give a reasonable representation.
 
 ~~~~ {.rust}
+# #![allow(unstable)]
 use chrono::{UTC, Offset};
 
 let dt = UTC.ymd(2014, 11, 28).and_hms(12, 0, 9);
-assert_eq!(dt.format("%Y-%m-%d %H:%M:%S").to_string(), "2014-11-28 12:00:09".to_string());
-assert_eq!(dt.format("%a %b %e %T %Y").to_string(), "Fri Nov 28 12:00:09 2014".to_string());
+assert_eq!(dt.format("%Y-%m-%d %H:%M:%S").to_string(), "2014-11-28 12:00:09");
+assert_eq!(dt.format("%a %b %e %T %Y").to_string(), "Fri Nov 28 12:00:09 2014");
 assert_eq!(dt.format("%a %b %e %T %Y").to_string(), dt.format("%c").to_string());
 
-assert_eq!(dt.to_string(), "2014-11-28T12:00:09Z".to_string());
+assert_eq!(dt.to_string(), "2014-11-28 12:00:09 UTC");
+assert_eq!(format!("{:?}", dt), "2014-11-28T12:00:09Z");
 ~~~~
 
 ### Individual date and time
@@ -137,6 +140,7 @@ Most operations available to `DateTime` are also available to `Date` and `Time`
 whenever appropriate.
 
 ~~~~ {.rust}
+# #![allow(unstable)]
 use chrono::{UTC, Local, Offset, LocalResult, Datelike, Weekday};
 
 # // these *may* fail, but only very rarely. just rerun the test if you were that unfortunate ;)
@@ -145,7 +149,7 @@ assert_eq!(Local::today(), Local::now().date());
 
 assert_eq!(UTC.ymd(2014, 11, 28).weekday(), Weekday::Fri);
 assert_eq!(UTC.ymd_opt(2014, 11, 31), LocalResult::None);
-assert_eq!(UTC.hms_milli(7, 8, 9, 10).format("%H%M%S").to_string(), "070809".to_string());
+assert_eq!(UTC.hms_milli(7, 8, 9, 10).format("%H%M%S").to_string(), "070809");
 ~~~~
 
 `DateTime` has two methods, `date` and `time`,
@@ -184,6 +188,7 @@ Advanced offset handling and date/time parsing is not yet supported (but is plan
 
 #![doc(html_root_url = "https://lifthrasiir.github.io/rust-chrono/")]
 
+#![allow(unstable)]
 #![deny(missing_docs)]
 
 extern crate "time" as stdtime;
diff --git a/src/naive/date.rs b/src/naive/date.rs
index 2ba71ab..bd3e137 100644
--- a/src/naive/date.rs
+++ b/src/naive/date.rs
@@ -6,7 +6,7 @@
  * ISO 8601 calendar date without timezone.
  */
 
-use std::fmt;
+use std::{fmt, hash};
 use std::num::{Int, ToPrimitive};
 use std::ops::{Add, Sub};
 
@@ -25,7 +25,7 @@ const MIN_YEAR: i32 = internals::MIN_YEAR as i32;
 /// ISO 8601 calendar date without timezone.
 /// Allows for every proleptic Gregorian date from Jan 1, 262145 BCE to Dec 31, 262143 CE.
 /// Also supports the conversion from ISO 8601 ordinal and week date.
-#[derive(PartialEq, Eq, PartialOrd, Ord, Copy, Clone, Hash)]
+#[derive(PartialEq, Eq, PartialOrd, Ord, Copy, Clone)]
 pub struct NaiveDate {
     ymdf: DateImpl, // (year << 13) | of
 }
@@ -40,8 +40,10 @@ pub const MAX: NaiveDate = NaiveDate { ymdf: (MAX_YEAR << 13) | (365 << 4) | 0o1
 fn test_date_bounds() {
     let calculated_min = NaiveDate::from_ymd(MIN_YEAR, 1, 1);
     let calculated_max = NaiveDate::from_ymd(MAX_YEAR, 12, 31);
-    assert!(MIN == calculated_min, "`MIN` should have a year flag {}", calculated_min.of().flags());
-    assert!(MAX == calculated_max, "`MAX` should have a year flag {}", calculated_max.of().flags());
+    assert!(MIN == calculated_min,
+            "`MIN` should have a year flag {:?}", calculated_min.of().flags());
+    assert!(MAX == calculated_max,
+            "`MAX` should have a year flag {:?}", calculated_max.of().flags());
 }
 
 impl NaiveDate {
@@ -378,6 +380,10 @@ impl Datelike for NaiveDate {
     }
 }
 
+impl<H: hash::Hasher + hash::Writer> hash::Hash<H> for NaiveDate {
+    fn hash(&self, state: &mut H) { self.ymdf.hash(state) }
+}
+
 impl Add<Duration> for NaiveDate {
     type Output = NaiveDate;
 
@@ -432,6 +438,18 @@ impl fmt::Show for NaiveDate {
     }
 }
 
+impl fmt::String for NaiveDate {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let year = self.year();
+        let mdf = self.mdf();
+        if year >= 0 {
+            write!(f, "{:04}-{:02}-{:02}", year, mdf.month(), mdf.day())
+        } else {
+            write!(f, "{:+05}-{:02}-{:02}", year, mdf.month(), mdf.day())
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::{NaiveDate, MIN, MAX};
@@ -736,35 +754,40 @@ mod tests {
 
     #[test]
     fn test_date_fmt() {
-        assert_eq!(NaiveDate::from_ymd(2012,  3, 4).to_string(),  "2012-03-04".to_string());
-        assert_eq!(NaiveDate::from_ymd(0,     3, 4).to_string(),  "0000-03-04".to_string());
-        assert_eq!(NaiveDate::from_ymd(-307,  3, 4).to_string(), "-0307-03-04".to_string());
-        assert_eq!(NaiveDate::from_ymd(12345, 3, 4).to_string(), "+12345-03-04".to_string());
+        assert_eq!(format!("{:?}", NaiveDate::from_ymd(2012,  3, 4)),   "2012-03-04");
+        assert_eq!(format!("{:?}", NaiveDate::from_ymd(0,     3, 4)),   "0000-03-04");
+        assert_eq!(format!("{:?}", NaiveDate::from_ymd(-307,  3, 4)),  "-0307-03-04");
+        assert_eq!(format!("{:?}", NaiveDate::from_ymd(12345, 3, 4)), "+12345-03-04");
+
+        assert_eq!(NaiveDate::from_ymd(2012,  3, 4).to_string(),  "2012-03-04");
+        assert_eq!(NaiveDate::from_ymd(0,     3, 4).to_string(),  "0000-03-04");
+        assert_eq!(NaiveDate::from_ymd(-307,  3, 4).to_string(), "-0307-03-04");
+        assert_eq!(NaiveDate::from_ymd(12345, 3, 4).to_string(), "12345-03-04");
 
         // the format specifier should have no effect on `NaiveTime`
-        assert_eq!(format!("{:+30}", NaiveDate::from_ymd(1234, 5, 6)), "1234-05-06".to_string());
-        assert_eq!(format!("{:30}", NaiveDate::from_ymd(12345, 6, 7)), "+12345-06-07".to_string());
+        assert_eq!(format!("{:+30?}", NaiveDate::from_ymd(1234, 5, 6)), "1234-05-06");
+        assert_eq!(format!("{:30?}", NaiveDate::from_ymd(12345, 6, 7)), "+12345-06-07");
     }
 
     #[test]
     fn test_date_format() {
         let d = NaiveDate::from_ymd(2012, 3, 4);
-        assert_eq!(d.format("%Y,%C,%y,%G,%g").to_string(), "2012,20,12,2012,12".to_string());
-        assert_eq!(d.format("%m,%b,%h,%B").to_string(), "03,Mar,Mar,March".to_string());
-        assert_eq!(d.format("%d,%e").to_string(), "04, 4".to_string());
-        assert_eq!(d.format("%U,%W,%V").to_string(), "10,09,09".to_string());
-        assert_eq!(d.format("%a,%A,%w,%u").to_string(), "Sun,Sunday,0,7".to_string());
-        assert_eq!(d.format("%j").to_string(), "064".to_string()); // since 2012 is a leap year
-        assert_eq!(d.format("%D,%x").to_string(), "03/04/12,03/04/12".to_string());
-        assert_eq!(d.format("%F").to_string(), "2012-03-04".to_string());
-        assert_eq!(d.format("%v").to_string(), " 4-Mar-2012".to_string());
-        assert_eq!(d.format("%t%n%%%n%t").to_string(), "\t\n%\n\t".to_string());
+        assert_eq!(d.format("%Y,%C,%y,%G,%g").to_string(), "2012,20,12,2012,12");
+        assert_eq!(d.format("%m,%b,%h,%B").to_string(), "03,Mar,Mar,March");
+        assert_eq!(d.format("%d,%e").to_string(), "04, 4");
+        assert_eq!(d.format("%U,%W,%V").to_string(), "10,09,09");
+        assert_eq!(d.format("%a,%A,%w,%u").to_string(), "Sun,Sunday,0,7");
+        assert_eq!(d.format("%j").to_string(), "064"); // since 2012 is a leap year
+        assert_eq!(d.format("%D,%x").to_string(), "03/04/12,03/04/12");
+        assert_eq!(d.format("%F").to_string(), "2012-03-04");
+        assert_eq!(d.format("%v").to_string(), " 4-Mar-2012");
+        assert_eq!(d.format("%t%n%%%n%t").to_string(), "\t\n%\n\t");
 
         // corner cases
         assert_eq!(NaiveDate::from_ymd(2007, 12, 31).format("%G,%g,%U,%W,%V").to_string(),
-                   "2008,08,53,53,01".to_string());
+                   "2008,08,53,53,01");
         assert_eq!(NaiveDate::from_ymd(2010, 1, 3).format("%G,%g,%U,%W,%V").to_string(),
-                   "2009,09,01,00,53".to_string());
+                   "2009,09,01,00,53");
     }
 }
 
@@ -860,10 +883,10 @@ mod internals {
 
     pub fn cycle_to_yo(cycle: u32) -> (u32, u32) {
         let (mut year_mod_400, mut ordinal0) = div_rem(cycle, 365);
-        let delta = YEAR_DELTAS[year_mod_400 as uint] as u32;
+        let delta = YEAR_DELTAS[year_mod_400 as usize] as u32;
         if ordinal0 < delta {
             year_mod_400 -= 1;
-            ordinal0 += 365 - YEAR_DELTAS[year_mod_400 as uint] as u32;
+            ordinal0 += 365 - YEAR_DELTAS[year_mod_400 as usize] as u32;
         } else {
             ordinal0 -= delta;
         }
@@ -871,7 +894,7 @@ mod internals {
     }
 
     pub fn yo_to_cycle(year_mod_400: u32, ordinal: u32) -> u32 {
-        year_mod_400 * 365 + YEAR_DELTAS[year_mod_400 as uint] as u32 + ordinal - 1
+        year_mod_400 * 365 + YEAR_DELTAS[year_mod_400 as usize] as u32 + ordinal - 1
     }
 
     impl YearFlags {
@@ -883,7 +906,7 @@ mod internals {
 
         #[inline]
         pub fn from_year_mod_400(year: i32) -> YearFlags {
-            YEAR_TO_FLAGS[year as uint]
+            YEAR_TO_FLAGS[year as usize]
         }
 
         #[inline]
@@ -903,7 +926,7 @@ mod internals {
         #[inline]
         pub fn nisoweeks(&self) -> u32 {
             let YearFlags(flags) = *self;
-            52 + ((0b00000100_00000110 >> flags as uint) & 1)
+            52 + ((0b00000100_00000110 >> flags as usize) & 1)
         }
     }
 
@@ -930,7 +953,7 @@ mod internals {
     pub const MAX_MDL: u32 = (12 << 6) | (31 << 1) | 1;
 
     const XX: i8 = -128;
-    static MDL_TO_OL: [i8; (MAX_MDL as uint + 1u)] = [
+    static MDL_TO_OL: [i8; (MAX_MDL as usize + 1us)] = [
          XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
          XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
          XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
@@ -985,7 +1008,7 @@ mod internals {
          98,100, 98,100, 98,100, 98,100, 98,100, 98,100, 98,100, 98,100, // 12
     ];
 
-    static OL_TO_MDL: [u8; (MAX_OL as uint + 1u)] = [
+    static OL_TO_MDL: [u8; (MAX_OL as usize + 1us)] = [
           0,  0,                                                         // 0
          64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
          64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
@@ -1059,7 +1082,7 @@ mod internals {
         #[inline]
         pub fn from_mdf(Mdf(mdf): Mdf) -> Of {
             let mdl = mdf >> 3;
-            match MDL_TO_OL.get(mdl as uint) {
+            match MDL_TO_OL.get(mdl as usize) {
                 Some(&v) => Of(mdf - ((v as i32 as u32 & 0x3ff) << 3)),
                 None => Of(0)
             }
@@ -1132,7 +1155,7 @@ mod internals {
     impl fmt::Show for Of {
         fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
             let Of(of) = *self;
-            write!(f, "Of(({} << 4) | {:#04o} /*{}*/)",
+            write!(f, "Of(({} << 4) | {:#04o} /*{:?}*/)",
                    of >> 4, of & 0b1111, YearFlags((of & 0b1111) as u8))
         }
     }
@@ -1166,7 +1189,7 @@ mod internals {
         #[inline]
         pub fn from_of(Of(of): Of) -> Mdf {
             let ol = of >> 3;
-            match OL_TO_MDL.get(ol as uint) {
+            match OL_TO_MDL.get(ol as usize) {
                 Some(&v) => Mdf(of + ((v as u32) << 3)),
                 None => Mdf(0)
             }
@@ -1176,7 +1199,7 @@ mod internals {
         pub fn valid(&self) -> bool {
             let Mdf(mdf) = *self;
             let mdl = mdf >> 3;
-            match MDL_TO_OL.get(mdl as uint) {
+            match MDL_TO_OL.get(mdl as usize) {
                 Some(&v) => v >= 0,
                 None => false
             }
@@ -1229,7 +1252,7 @@ mod internals {
     impl fmt::Show for Mdf {
         fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
             let Mdf(mdf) = *self;
-            write!(f, "Mdf(({} << 9) | ({} << 4) | {:#04o} /*{}*/)",
+            write!(f, "Mdf(({} << 9) | ({} << 4) | {:#04o} /*{:?}*/)",
                    mdf >> 9, (mdf >> 4) & 0b11111, mdf & 0b1111, YearFlags((mdf & 0b1111) as u8))
         }
     }
@@ -1298,7 +1321,7 @@ mod internals {
                 for ordinal in range_inclusive(ordinal1, ordinal2) {
                     let of = Of::new(ordinal, flags);
                     assert!(of.valid() == expected,
-                            "ordinal {} = {} should be {} for dominical year {}",
+                            "ordinal {} = {:?} should be {} for dominical year {:?}",
                             ordinal, of, if expected {"valid"} else {"invalid"}, flags);
                 }
             }
@@ -1326,7 +1349,7 @@ mod internals {
                     for day in range_inclusive(day1, day2) {
                         let mdf = Mdf::new(month, day, flags);
                         assert!(mdf.valid() == expected,
-                                "month {} day {} = {} should be {} for dominical year {}",
+                                "month {} day {} = {:?} should be {} for dominical year {:?}",
                                 month, day, mdf, if expected {"valid"} else {"invalid"}, flags);
                     }
                 }
diff --git a/src/naive/datetime.rs b/src/naive/datetime.rs
index f9e5e4f..f531845 100644
--- a/src/naive/datetime.rs
+++ b/src/naive/datetime.rs
@@ -6,7 +6,7 @@
  * ISO 8601 date and time without timezone.
  */
 
-use std::fmt;
+use std::{fmt, hash};
 use std::num::{Int, ToPrimitive};
 use std::ops::{Add, Sub};
 
@@ -18,7 +18,7 @@ use naive::date::NaiveDate;
 use format::DelayedFormat;
 
 /// ISO 8601 combined date and time without timezone.
-#[derive(PartialEq, Eq, PartialOrd, Ord, Copy, Clone, Hash)]
+#[derive(PartialEq, Eq, PartialOrd, Ord, Copy, Clone)]
 pub struct NaiveDateTime {
     date: NaiveDate,
     time: NaiveTime,
@@ -163,6 +163,10 @@ impl Timelike for NaiveDateTime {
     }
 }
 
+impl<H: hash::Hasher + hash::Writer> hash::Hash<H> for NaiveDateTime {
+    fn hash(&self, state: &mut H) { self.date.hash(state); self.time.hash(state) }
+}
+
 impl Add<Duration> for NaiveDateTime {
     type Output = NaiveDateTime;
 
@@ -203,7 +207,13 @@ impl Sub<Duration> for NaiveDateTime {
 
 impl fmt::Show for NaiveDateTime {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}T{}", self.date, self.time)
+        write!(f, "{:?}T{:?}", self.date, self.time)
+    }
+}
+
+impl fmt::String for NaiveDateTime {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{} {}", self.date, self.time)
     }
 }
 
@@ -270,8 +280,8 @@ mod tests {
     #[test]
     fn test_datetime_format() {
         let dt = NaiveDate::from_ymd(2010, 9, 8).and_hms_milli(7, 6, 54, 321);
-        assert_eq!(dt.format("%c").to_string(), "Wed Sep  8 07:06:54 2010".to_string());
-        assert_eq!(dt.format("%t%n%%%n%t").to_string(), "\t\n%\n\t".to_string());
+        assert_eq!(dt.format("%c").to_string(), "Wed Sep  8 07:06:54 2010");
+        assert_eq!(dt.format("%t%n%%%n%t").to_string(), "\t\n%\n\t");
     }
 }
 
diff --git a/src/naive/time.rs b/src/naive/time.rs
index 70e1c90..0a50e46 100644
--- a/src/naive/time.rs
+++ b/src/naive/time.rs
@@ -6,7 +6,7 @@
  * ISO 8601 time without timezone.
  */
 
-use std::fmt;
+use std::{fmt, hash};
 use std::num::Int;
 use std::ops::{Add, Sub};
 
@@ -18,7 +18,7 @@ use format::DelayedFormat;
 
 /// ISO 8601 time without timezone.
 /// Allows for the nanosecond precision and optional leap second representation.
-#[derive(PartialEq, Eq, PartialOrd, Ord, Copy, Clone, Hash)]
+#[derive(PartialEq, Eq, PartialOrd, Ord, Copy, Clone)]
 pub struct NaiveTime {
     secs: u32,
     frac: u32,
@@ -172,6 +172,10 @@ impl Timelike for NaiveTime {
     }
 }
 
+impl<H: hash::Hasher + hash::Writer> hash::Hash<H> for NaiveTime {
+    fn hash(&self, state: &mut H) { self.secs.hash(state); self.frac.hash(state) }
+}
+
 impl Add<Duration> for NaiveTime {
     type Output = NaiveTime;
 
@@ -241,6 +245,10 @@ impl fmt::Show for NaiveTime {
     }
 }
 
+impl fmt::String for NaiveTime {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Show::fmt(self, f) }
+}
+
 #[cfg(test)]
 mod tests {
     use super::NaiveTime;
@@ -350,36 +358,29 @@ mod tests {
 
     #[test]
     fn test_time_fmt() {
-        assert_eq!(NaiveTime::from_hms_milli(23, 59, 59, 999).to_string(),
-                   "23:59:59.999".to_string());
-        assert_eq!(NaiveTime::from_hms_milli(23, 59, 59, 1_000).to_string(),
-                   "23:59:60".to_string());
-        assert_eq!(NaiveTime::from_hms_milli(23, 59, 59, 1_001).to_string(),
-                   "23:59:60.001".to_string());
-        assert_eq!(NaiveTime::from_hms_micro(0, 0, 0, 43210).to_string(),
-                   "00:00:00.043210".to_string());
-        assert_eq!(NaiveTime::from_hms_nano(0, 0, 0, 6543210).to_string(),
-                   "00:00:00.006543210".to_string());
+        assert_eq!(format!("{}", NaiveTime::from_hms_milli(23, 59, 59, 999)), "23:59:59.999");
+        assert_eq!(format!("{}", NaiveTime::from_hms_milli(23, 59, 59, 1_000)), "23:59:60");
+        assert_eq!(format!("{}", NaiveTime::from_hms_milli(23, 59, 59, 1_001)), "23:59:60.001");
+        assert_eq!(format!("{}", NaiveTime::from_hms_micro(0, 0, 0, 43210)), "00:00:00.043210");
+        assert_eq!(format!("{}", NaiveTime::from_hms_nano(0, 0, 0, 6543210)), "00:00:00.006543210");
 
         // the format specifier should have no effect on `NaiveTime`
-        assert_eq!(format!("{:30}", NaiveTime::from_hms_milli(3, 5, 7, 9)),
-                   "03:05:07.009".to_string());
+        assert_eq!(format!("{:30}", NaiveTime::from_hms_milli(3, 5, 7, 9)), "03:05:07.009");
     }
 
     #[test]
     fn test_time_format() {
         let t = NaiveTime::from_hms_nano(3, 5, 7, 98765432);
-        assert_eq!(t.format("%H,%k,%I,%l,%P,%p").to_string(), "03, 3,03, 3,am,AM".to_string());
-        assert_eq!(t.format("%M").to_string(), "05".to_string());
-        assert_eq!(t.format("%S,%f").to_string(), "07,098765432".to_string());
-        assert_eq!(t.format("%R").to_string(), "03:05".to_string());
-        assert_eq!(t.format("%T,%X").to_string(), "03:05:07,03:05:07".to_string());
-        assert_eq!(t.format("%r").to_string(), "03:05:07 AM".to_string());
-        assert_eq!(t.format("%t%n%%%n%t").to_string(), "\t\n%\n\t".to_string());
+        assert_eq!(t.format("%H,%k,%I,%l,%P,%p").to_string(), "03, 3,03, 3,am,AM");
+        assert_eq!(t.format("%M").to_string(), "05");
+        assert_eq!(t.format("%S,%f").to_string(), "07,098765432");
+        assert_eq!(t.format("%R").to_string(), "03:05");
+        assert_eq!(t.format("%T,%X").to_string(), "03:05:07,03:05:07");
+        assert_eq!(t.format("%r").to_string(), "03:05:07 AM");
+        assert_eq!(t.format("%t%n%%%n%t").to_string(), "\t\n%\n\t");
 
         // corner cases
-        assert_eq!(NaiveTime::from_hms(13, 57, 9).format("%r").to_string(),
-                   "01:57:09 PM".to_string());
+        assert_eq!(NaiveTime::from_hms(13, 57, 9).format("%r").to_string(), "01:57:09 PM");
     }
 }
 
diff --git a/src/offset.rs b/src/offset.rs
index 4adccc6..cbdc1ca 100644
--- a/src/offset.rs
+++ b/src/offset.rs
@@ -6,9 +6,7 @@
  * Offsets from the local time to UTC.
  */
 
-use std::borrow::IntoCow;
 use std::fmt;
-use std::string::CowString;
 use stdtime;
 
 use {Weekday, Datelike, Timelike};
@@ -125,14 +123,14 @@ impl<Off:Offset> LocalResult<Date<Off>> {
 
 }
 
-impl<T:fmt::Show> LocalResult<T> {
+impl<T: fmt::Show> LocalResult<T> {
     /// Returns the single unique conversion result, or fails accordingly.
     pub fn unwrap(self) -> T {
         match self {
             LocalResult::None => panic!("No such local time"),
             LocalResult::Single(t) => t,
             LocalResult::Ambiguous(t1,t2) => {
-                panic!("Ambiguous local time, ranging from {} to {}", t1, t2)
+                panic!("Ambiguous local time, ranging from {:?} to {:?}", t1, t2)
             }
         }
     }
@@ -293,9 +291,6 @@ pub trait Offset: Clone + fmt::Show {
         }
     }
 
-    /// Returns a name or abbreviation of this offset.
-    fn name(&self) -> CowString<'static>;
-
     /// Returns the *current* offset from UTC to the local time.
     fn local_minus_utc(&self) -> Duration;
 
@@ -338,7 +333,6 @@ impl UTC {
 }
 
 impl Offset for UTC {
-    fn name(&self) -> CowString<'static> { "UTC".into_cow() }
     fn local_minus_utc(&self) -> Duration { Duration::zero() }
 
     fn from_local_date(&self, local: &NaiveDate) -> LocalResult<Date<UTC>> {
@@ -360,6 +354,10 @@ impl fmt::Show for UTC {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "Z") }
 }
 
+impl fmt::String for UTC {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "UTC") }
+}
+
 /// The fixed offset, from UTC-23:59:59 to UTC+23:59:59.
 #[derive(Copy, Clone, PartialEq, Eq)]
 pub struct FixedOffset {
@@ -409,7 +407,6 @@ impl FixedOffset {
 }
 
 impl Offset for FixedOffset {
-    fn name(&self) -> CowString<'static> { "UTC".into_cow() } // XXX
     fn local_minus_utc(&self) -> Duration { Duration::seconds(self.local_minus_utc as i64) }
 
     fn from_local_date(&self, local: &NaiveDate) -> LocalResult<Date<FixedOffset>> {
@@ -451,6 +448,10 @@ impl fmt::Show for FixedOffset {
     }
 }
 
+impl fmt::String for FixedOffset {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Show::fmt(self, f) }
+}
+
 /// The local timescale. This is implemented via the standard `time` crate.
 #[derive(Copy, Clone)]
 pub struct Local {
@@ -505,7 +506,6 @@ impl Local {
 }
 
 impl Offset for Local {
-    fn name(&self) -> CowString<'static> { "LMT".into_cow() } // XXX XXX
     fn local_minus_utc(&self) -> Duration { self.cached.local_minus_utc() }
 
     fn from_local_date(&self, local: &NaiveDate) -> LocalResult<Date<Local>> {
diff --git a/src/time.rs b/src/time.rs
index cc6404f..19337c8 100644
--- a/src/time.rs
+++ b/src/time.rs
@@ -44,17 +44,19 @@ impl<Off:Offset> Time<Off> {
         Time::from_utc(self.time, offset)
     }
 
+    /// Returns a view to the local time.
+    fn local(&self) -> NaiveTime {
+        self.offset.to_local_time(&self.time)
+    }
+}
+
+impl<Off: Offset + fmt::String> Time<Off> {
     /// Formats the time in the specified format string.
     /// See the `format` module on the supported escape sequences.
     #[inline]
     pub fn format<'a>(&'a self, fmt: &'a str) -> DelayedFormat<'a> {
         DelayedFormat::new_with_offset(None, Some(self.local()), &self.offset, fmt)
     }
-
-    /// Returns a view to the local time.
-    fn local(&self) -> NaiveTime {
-        self.offset.to_local_time(&self.time)
-    }
 }
 
 impl<Off:Offset> Timelike for Time<Off> {
@@ -108,8 +110,8 @@ impl<Off:Offset> Ord for Time<Off> {
     fn cmp(&self, other: &Time<Off>) -> Ordering { self.time.cmp(&other.time) }
 }
 
-impl<Off:Offset> hash::Hash for Time<Off> {
-    fn hash(&self, state: &mut hash::sip::SipState) { self.time.hash(state) }
+impl<Off: Offset, H: hash::Hasher + hash::Writer> hash::Hash<H> for Time<Off> {
+    fn hash(&self, state: &mut H) { self.time.hash(state) }
 }
 
 impl<Off:Offset> Add<Duration> for Time<Off> {
@@ -133,7 +135,13 @@ impl<Off:Offset> Sub<Duration> for Time<Off> {
     fn sub(self, rhs: Duration) -> Time<Off> { self.add(-rhs) }
 }
 
-impl<Off:Offset> fmt::Show for Time<Off> {
+impl<Off: Offset> fmt::Show for Time<Off> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{:?}{:?}", self.local(), self.offset)
+    }
+}
+
+impl<Off: Offset + fmt::String> fmt::String for Time<Off> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{}{}", self.local(), self.offset)
     }