lshort

    pub struct Edge {
        to:     char,
        from:   char,
        weight: int
    }

    pub struct digraph {
        _vertices:  Vec<char>,
        _adj_list:  HashMap<char, Vec<(char,int)> >
    }

lshort

    auto show_fail = [] () { cout << "Caught Expected Exception..." << endl; };
    auto show_err = [] (int ignore) { cout << "Failed to Catch Exception!!!"; };

    auto fail1 = [z] () { graph_tests(z,'A','D', set<string>{"Topsort"});
                          return 1; };
    expect_exception(fail1, true, show_fail, show_err );

    auto fail2 = [x, none] () { graph_tests(x,'A','D', none); return 1; };
    expect_exception(fail2, true, show_fail, show_err );

lshort

    unordered_map<string,string> expected_results_y {
        {"BFS","BFS visiting {A,B,E,C,D,}"},
        {"DFS","DFS visiting {A,E,B,C,D,}"},
        {"Topsort", "Topsort visiting {A,E,B,C,D,}"},
        {"Dijkstra", "Dijkstra visiting {A,E,D,}"},
        {"Bellman", "Bellman visiting {(E:A),(D:E),(C:B),(B:A),(A:-),}"}
    };
    graph_tests(y,'A','D', none, expected_results_y);

lshort

template<typename ExecLambda, typename OnThrowLambda, typename NoThrowLambda>
auto expect_exception( ExecLambda exec_lambda, bool expect_to_throw,
                       OnThrowLambda throw_lambda, NoThrowLambda no_throw_lambda,
                       decltype(throw_lambda()) expected_return_value)
{
    bool threw;
    decltype( exec_lambda() ) x;
    
    try {
        x = exec_lambda();

lshort

void graph_tests(const digraph &g, digraph::nodename source,
                digraph::nodename destination, const set<string> & except_on )
{
    auto throw_return = [] ()
        { cout << "Caught Expected Exception" << endl; };
    auto tst = [exc_return, except_on] (string fcn, auto a)
        {
            bool expect_throw = except_on.end()!=except_on.find(fcn);
            auto normal_return = [fcn] (auto retval)
                { cout << fcn << " visiting " << retval << endl; };

lshort

template<typename ExecLambda, typename OnThrowLambda, typename NoThrowLambda>
auto expect_exception( ExecLambda exec_lambda, bool expect_to_throw,
                       OnThrowLambda exc_lambda, NoThrowLambda no_exc_lambda)
{
    bool threw;
    decltype( exec_lambda() ) x;

    try {
        x = exec_lambda();
        threw = false;

lshort

template<typename ExecLambda>
void expect_exception( ExecLambda exec_lambda, bool expect_to_throw)
{
   bool threw;
   decltype( exec_lambda() ) x;
   try {
       x = exec_lambda();
       threw = false;
   }
   catch (...) {

lshort

  template<typename return_type, typename arg1_type, typename ...params>
  auto _L1( return_type (*fp) (arg1_type x, params...args), arg1_type x)
    { return [fp, x] (params...args) { return fp(x,args...); };  };

  double mult(double x, double y) { return x*y; }
  auto to_radians = _L1(mult,M_PI/180.0);
  auto cos_in_degrees = _L(cos) * to_radians;
  cout << cos_in_degrees(45.0) << endl;

lshort

  auto incr = [](auto a) {return a+1;};
  int add1(int x)  { return x+1; }
  int sub1(int x)  { return x-1; }

  auto ident = _L(add1) * _L(sub1);
  auto ident2 = incr * _L(sub1);
  cout << ident(1) << "," << ident2(1) << endl;

lshort

 template<typename return_type, typename ...params>
  auto _L( return_type (*fp) (params... args))
      { return [fp] (params... args) { return fp(args...); }; };