---

yaml
---
r: 14257
b: refs/heads/try
c: 8309d50
h: refs/heads/master
i:
  14255: 5ee4033
v: v3

Author: brson

[refs]

@@ -2,5 +2,5 @@
 refs/heads/master: 61b1875c16de39c166b0f4d54bba19f9c6777d1a
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: 4a81779abd786ff22d71434c6d9a5917ea4cdfff
-refs/heads/try: e360ddbd65e2501028f80e17a1ec7ad92904f39c
+refs/heads/try: 8309d50ff4ead4dd58b8f3c8388d5668e2e0d152
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105

branches/try/src/libcore/iter.rs

@@ -57,6 +57,16 @@ fn filter<A,IA:iterable<A>>(self: IA, prd: fn@(A) -> bool, blk: fn(A)) {
     }
 }
 
+fn filter_map<A,B,IA:iterable<A>>(self: IA, cnv: fn@(A) -> option<B>,
+                                  blk: fn(B)) {
+    self.iter {|a|
+        alt cnv(a) {
+          some(b) { blk(b) }
+          none { }
+        }
+    }
+}
+
 fn map<A,B,IA:iterable<A>>(self: IA, cnv: fn@(A) -> B, blk: fn(B)) {
     self.iter {|a|
         let b = cnv(a);
@@ -188,6 +198,21 @@ fn test_filter_on_uint_range() {
     assert l == [0u, 2u, 4u, 6u, 8u];
 }
 
+#[test]
+fn test_filter_map() {
+    fn negativate_the_evens(&&i: int) -> option<int> {
+        if i % 2 == 0 {
+            some(-i)
+        } else {
+            none
+        }
+    }
+
+    let l = to_list(bind filter_map(
+        bind int::range(0, 5, _), negativate_the_evens, _));
+    assert l == [0, -2, -4];
+}
+
 #[test]
 fn test_flat_map_with_option() {
     fn if_even(&&i: int) -> option<int> {