Revert the need for initial values with arithmetic iterators

src/libcollections/slice.rs

@@ -228,7 +228,7 @@ fn new_pos(i: uint, s: Direction) -> uint {
     #[inline]
     fn size_hint(&self) -> (uint, Option<uint>) {
         // For a vector of size n, there are exactly n! permutations.
-        let n = range(2, self.sdir.len() + 1).product(1);
+        let n = range(2, self.sdir.len() + 1).product();
         (n - self.swaps_made, Some(n - self.swaps_made))
     }
 }

src/libcollections/str.rs

@@ -116,7 +116,7 @@ fn concat(&self) -> String {
         }
 
         // `len` calculation may overflow but push_str will check boundaries
-        let len = self.iter().map(|s| s.as_slice().len()).sum(0);
+        let len = self.iter().map(|s| s.as_slice().len()).sum();
 
         let mut result = String::with_capacity(len);
 
@@ -140,7 +140,7 @@ fn connect(&self, sep: &str) -> String {
         // this is wrong without the guarantee that `self` is non-empty
         // `len` calculation may overflow but push_str but will check boundaries
         let len = sep.len() * (self.len() - 1)
-            + self.iter().map(|s| s.as_slice().len()).sum(0);
+            + self.iter().map(|s| s.as_slice().len()).sum();
         let mut result = String::with_capacity(len);
         let mut first = true;
 
@@ -2151,7 +2151,7 @@ fn t<S: Default + Str>() {
     #[test]
     fn test_str_container() {
         fn sum_len(v: &[&str]) -> uint {
-            v.iter().map(|x| x.len()).sum(0)
+            v.iter().map(|x| x.len()).sum()
         }
 
         let s = String::from_str("01234");

src/libcore/iter.rs

@@ -63,7 +63,7 @@ trait defined in this module. For loops can be viewed as a syntactical expansion
 use cmp::Ord;
 use mem;
 use num::{ToPrimitive, Int};
-use ops::{Add, Mul};
+use ops::Add;
 use option::{Option, Some, None};
 use uint;
 #[deprecated = "renamed to Extend"] pub use self::Extend as Extendable;
@@ -402,7 +402,7 @@ fn fuse(self) -> Fuse<Self> {
     ///             .inspect(|&x| println!("filtering {}", x))
     ///             .filter(|&x| x % 2 == 0)
     ///             .inspect(|&x| println!("{} made it through", x))
-    ///             .sum(0);
+    ///             .sum();
     /// println!("{}", sum);
     /// ```
     #[inline]
@@ -784,17 +784,33 @@ pub trait AdditiveIterator<A> {
     ///
     /// let a = [1i, 2, 3, 4, 5];
     /// let mut it = a.iter().map(|&x| x);
-    /// assert!(it.sum(0) == 15);
+    /// assert!(it.sum() == 15);
     /// ```
-    fn sum(&mut self, init: A) -> A;
+    fn sum(&mut self) -> A;
 }
 
-impl<A: Add<A, A>, T: Iterator<A>> AdditiveIterator<A> for T {
+macro_rules! impl_additive {
+    ($A:ty, $init:expr) => {
+        impl<T: Iterator<$A>> AdditiveIterator<$A> for T {
             #[inline]
-    fn sum(&mut self, init: A) -> A {
-        self.fold(init, |s, x| s + x)
+            fn sum(&mut self) -> $A {
+                self.fold($init, |acc, x| acc + x)
             }
+        }
+    };
 }
+impl_additive!(i8,   0)
+impl_additive!(i16,  0)
+impl_additive!(i32,  0)
+impl_additive!(i64,  0)
+impl_additive!(int,  0)
+impl_additive!(u8,   0)
+impl_additive!(u16,  0)
+impl_additive!(u32,  0)
+impl_additive!(u64,  0)
+impl_additive!(uint, 0)
+impl_additive!(f32,  0.0)
+impl_additive!(f64,  0.0)
 
 /// A trait for iterators over elements which can be multiplied together.
 pub trait MultiplicativeIterator<A> {
@@ -806,21 +822,37 @@ pub trait MultiplicativeIterator<A> {
     /// use std::iter::{count, MultiplicativeIterator};
     ///
     /// fn factorial(n: uint) -> uint {
-    ///     count(1u, 1).take_while(|&i| i <= n).product(1)
+    ///     count(1u, 1).take_while(|&i| i <= n).product()
     /// }
     /// assert!(factorial(0) == 1);
     /// assert!(factorial(1) == 1);
     /// assert!(factorial(5) == 120);
     /// ```
-    fn product(&mut self, init: A) -> A;
+    fn product(&mut self) -> A;
 }
 
-impl<A: Mul<A, A>, T: Iterator<A>> MultiplicativeIterator<A> for T {
+macro_rules! impl_multiplicative {
+    ($A:ty, $init:expr) => {
+        impl<T: Iterator<$A>> MultiplicativeIterator<$A> for T {
             #[inline]
-    fn product(&mut self, init: A) -> A {
-        self.fold(init, |p, x| p * x)
+            fn product(&mut self) -> $A {
+                self.fold($init, |acc, x| acc * x)
             }
+        }
+    };
 }
+impl_multiplicative!(i8,   1)
+impl_multiplicative!(i16,  1)
+impl_multiplicative!(i32,  1)
+impl_multiplicative!(i64,  1)
+impl_multiplicative!(int,  1)
+impl_multiplicative!(u8,   1)
+impl_multiplicative!(u16,  1)
+impl_multiplicative!(u32,  1)
+impl_multiplicative!(u64,  1)
+impl_multiplicative!(uint, 1)
+impl_multiplicative!(f32,  1.0)
+impl_multiplicative!(f64,  1.0)
 
 /// A trait for iterators over elements which can be compared to one another.
 pub trait OrdIterator<A> {

src/libcoretest/iter.rs

@@ -294,17 +294,17 @@ fn test_iterator_len() {
 #[test]
 fn test_iterator_sum() {
     let v: &[_] = &[0i, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-    assert_eq!(v[0..4].iter().map(|&x| x).sum(0), 6);
-    assert_eq!(v.iter().map(|&x| x).sum(0), 55);
-    assert_eq!(v[0..0].iter().map(|&x| x).sum(0), 0);
+    assert_eq!(v[0..4].iter().map(|&x| x).sum(), 6);
+    assert_eq!(v.iter().map(|&x| x).sum(), 55);
+    assert_eq!(v[0..0].iter().map(|&x| x).sum(), 0);
 }
 
 #[test]
 fn test_iterator_product() {
     let v: &[_] = &[0i, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-    assert_eq!(v[0..4].iter().map(|&x| x).product(1), 0);
-    assert_eq!(v[1..5].iter().map(|&x| x).product(1), 24);
-    assert_eq!(v[0..0].iter().map(|&x| x).product(1), 1);
+    assert_eq!(v[0..4].iter().map(|&x| x).product(), 0);
+    assert_eq!(v[1..5].iter().map(|&x| x).product(), 24);
+    assert_eq!(v[0..0].iter().map(|&x| x).product(), 1);
 }
 
 #[test]

src/librustc/middle/check_match.rs

@@ -70,7 +70,7 @@ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
             pretty_printed_matrix.iter().map(|row| row[col].len()).max().unwrap_or(0u)
         }).collect();
 
-        let total_width = column_widths.iter().map(|n| *n).sum(0) + column_count * 3 + 1;
+        let total_width = column_widths.iter().map(|n| *n).sum() + column_count * 3 + 1;
         let br = String::from_char(total_width, '+');
         try!(write!(f, "{}\n", br));
         for row in pretty_printed_matrix.into_iter() {

src/librustc/middle/trans/_match.rs

@@ -756,7 +756,7 @@ fn pat_score(def_map: &DefMap, pat: &ast::Pat) -> uint {
         let total_score = m.iter()
             .map(|row| row.pats[col])
             .map(|pat| pat_score(def_map, pat))
-            .sum(0);
+            .sum();
 
         // Irrefutable columns always go first, they'd only be duplicated in the branches.
         if total_score == 0 {

src/librustc/middle/typeck/astconv.rs

@@ -1194,7 +1194,7 @@ fn ty_of_method_or_bare_fn<'tcx, AC: AstConv<'tcx>>(
             lifetimes_for_params.push((input_pat, accumulator));
         }
 
-        if lifetimes_for_params.iter().map(|&(_, ref x)| x.len()).sum(0) == 1 {
+        if lifetimes_for_params.iter().map(|&(_, ref x)| x.len()).sum() == 1 {
             implied_output_region =
                 Some(lifetimes_for_params.iter()
                                          .filter_map(|&(_, ref x)|

src/librustdoc/stability_summary.rs

@@ -15,7 +15,6 @@
 
 use std::ops::Add;
 use std::num::Zero;
-use std::iter::AdditiveIterator;
 
 use syntax::attr::{Deprecated, Experimental, Unstable, Stable, Frozen, Locked};
 use syntax::ast::Public;
@@ -152,14 +151,14 @@ fn summarize_item(item: &Item) -> (Counts, Option<ModuleSummary>) {
             let subcounts = subitems.iter().filter(|i| visible(*i))
                                            .map(summarize_item)
                                            .map(|s| s.val0())
-                                           .sum(Counts::zero());
+                                           .fold(Counts::zero(), |acc, x| acc + x);
             (item_counts + subcounts, None)
         }
         // `pub` automatically
         EnumItem(Enum { variants: ref subitems, .. }) => {
             let subcounts = subitems.iter().map(summarize_item)
                                            .map(|s| s.val0())
-                                           .sum(Counts::zero());
+                                           .fold(Counts::zero(), |acc, x| acc + x);
             (item_counts + subcounts, None)
         }
         TraitItem(Trait {
@@ -177,7 +176,7 @@ fn extract_item<'a>(trait_item: &'a TraitMethod) -> &'a Item {
                                        .map(extract_item)
                                        .map(summarize_item)
                                        .map(|s| s.val0())
-                                       .sum(Counts::zero());
+                                       .fold(Counts::zero(), |acc, x| acc + x);
             (item_counts + subcounts, None)
         }
         ModuleItem(Module { ref items, .. }) => {

src/libstd/path/posix.rs

@@ -356,7 +356,7 @@ fn normalize<V: AsSlice<u8>>(v: V) -> Vec<u8> {
                         Some(vec![SEP_BYTE])
                     } else {
                         let n = if is_abs { comps.len() } else { comps.len() - 1} +
-                                comps.iter().map(|v| v.len()).sum(0);
+                                comps.iter().map(|v| v.len()).sum();
                         let mut v = Vec::with_capacity(n);
                         let mut it = comps.into_iter();
                         if !is_abs {

src/libstd/path/windows.rs

@@ -781,7 +781,7 @@ fn normalize__(s: &str, prefix: Option<PathPrefix>) -> Option<String> {
                         let prefix_ = s.slice_to(prefix_len(prefix));
                         let n = prefix_.len() +
                                 if is_abs { comps.len() } else { comps.len() - 1} +
-                                comps.iter().map(|v| v.len()).sum(0);
+                                comps.iter().map(|v| v.len()).sum();
                         let mut s = String::with_capacity(n);
                         match prefix {
                             Some(DiskPrefix) => {

src/libunicode/u_str.rs

@@ -153,7 +153,7 @@ fn is_alphanumeric(&self) -> bool { self.chars().all(u_char::is_alphanumeric) }
 
     #[inline]
     fn width(&self, is_cjk: bool) -> uint {
-        self.chars().map(|c| c.width(is_cjk).unwrap_or(0)).sum(0)
+        self.chars().map(|c| c.width(is_cjk).unwrap_or(0)).sum()
     }
 
     #[inline]

src/test/bench/shootout-spectralnorm.rs

@@ -105,7 +105,7 @@ fn A(i: uint, j: uint) -> f64 {
 }
 
 fn dot(v: &[f64], u: &[f64]) -> f64 {
-    v.iter().zip(u.iter()).map(|(a, b)| *a * *b).sum(0.0)
+    v.iter().zip(u.iter()).map(|(a, b)| *a * *b).sum()
 }
 
 // Executes a closure in parallel over the given mutable slice. The closure `f`

src/test/run-pass/issue-15673.rs

@@ -11,5 +11,5 @@
 use std::iter::AdditiveIterator;
 fn main() {
     let x: [u64, ..3] = [1, 2, 3];
-    assert_eq!(6, range(0, 3).map(|i| x[i]).sum(0));
+    assert_eq!(6, range(0, 3).map(|i| x[i]).sum());
 }