stdlib: Add vec::concat to concatenate a vector of vectors

Compare to str::concat

src/lib/vec.rs

@@ -446,6 +446,19 @@ fn filter<T>(f: block(T) -> bool, v: [mutable? T]) -> [T] {
     ret result;
 }
 
+/*
+Function: concat
+
+Concatenate a vector of vectors. Flattens a vector of vectors of T into
+a single vector of T.
+*/
+fn concat<T>(v: [mutable? [mutable? T]]) -> [T] {
+    // FIXME: So much copying
+    let new: [T] = [];
+    for inner: [T] in v { new += inner; }
+    ret new;
+}
+
 /*
 Function: foldl
 

src/test/stdtest/vec.rs

@@ -469,6 +469,11 @@ fn init_empty() {
 #[ignore]
 fn init_empty() { }
 
+#[test]
+fn concat() {
+    assert vec::concat([[1], [2,3]]) == [1, 2, 3];
+}
+
 // Local Variables:
 // mode: rust;
 // fill-column: 78;