pretty_print_infix_catamorphism.cpp

expression e = add({
   cst(1),
   cst(2),
   mul({cst(0), var("x"), var("y")}),
   mul({cst(1), var("y"), add({cst(2), var("x")})}),
   add({cst(0), var("x")})
   });

std::cout << cata<std::string>(print_infix_bad, e) << std::endl;

// Outputs =>
1 + 2 + (0) * (x) * (y) + (1) * (y) * (2 + x) + 0 + x