code.rs

trait GraphAlgorithm<Node, Edge> {
    fn dfs_rec(&self, source: &Node, visitor: |&Node| -> (), visited: &mut HashSet<&Node>);
}

impl<'a, Node:Hash+Eq, Edge> GraphAlgorithm<Node, Edge> for &'a Graph<Node, Edge> {
    fn dfs_rec<'a>(&self, source: &Node, visitor: |&Node| -> (), visited: &'a mut HashSet<&Node>) {
       visitor(source);
            self.children(source, |target,_| {
                if !visited.contains(&target) {
                //    visited.insert(target);
                //    self.dfs_rec(target, visitor, visited);
                };
            });
    }

}

compile_out

src/graph.rs:40:38: 40:45 error: mismatched types: expected `&&Node` but found `&&Node` (lifetime mismatch)
src/graph.rs:40                 if !visited.contains(&target) {
                                                     ^~~~~~~
src/graph.rs:39:46: 44:14 note: an anonymous lifetime defined on the block at 39:45...
src/graph.rs:39             self.children(source, |target,_| {
src/graph.rs:40                 if !visited.contains(&target) {
src/graph.rs:41                 //    visited.insert(target);
src/graph.rs:42                 //    self.dfs_rec(target, visitor, visited);
src/graph.rs:43                 };
src/graph.rs:44             });
src/graph.rs:37:99: 45:6 note: ...does not necessarily outlive the anonymous lifetime #4 defined on the block at 37:98
src/graph.rs:37     fn dfs_rec<'a>(&self, source: &Node, visitor: |&Node| -> (), visited: &'a mut HashSet<&Node>) {
src/graph.rs:38        visitor(source);
src/graph.rs:39             self.children(source, |target,_| {
src/graph.rs:40                 if !visited.contains(&target) {
src/graph.rs:41                 //    visited.insert(target);
src/graph.rs:42                 //    self.dfs_rec(target, visitor, visited);
                ...
error: aborting due to previous error