Add comments.

examples/quickstart/quickstart.cpp

@@ -8,34 +8,46 @@
 namespace {
 auto run(std::string_view const text, bool verbose) -> bool {
 	try {
+		// parse text into an expression
 		auto expr = kalcy::Parser{text}.parse();
 		assert(expr != nullptr);
+		// evaluate parsed expression
+		// a custom Env can be used and passed, if desired
 		std::cout << kalcy::evaluate(*expr) << "\n";
+		// print AST if verbose
 		if (verbose) { std::cout << std::format("expression\t: {}\nAST\t\t: {}\n", text, kalcy::to_string(*expr)); }
 		return true;
 	} catch (kalcy::Error const& err) {
+		// print error
 		std::cerr << err.what() << "\n";
+		// highlight error location under text
 		std::cerr << " | " << text << "\n | " << err.build_highlight() << "\n";
 		return false;
 	}
 }
 } // namespace
 
 auto main(int argc, char** argv) -> int {
+	// obtain arguments, skip exe name
 	auto args = std::span{argv, static_cast<std::size_t>(argc)}.subspan(1);
 
 	bool verbose{};
+	// check if verbose
 	if (args.front() == std::string_view{"-v"}) {
-		args = args.subspan(1);
 		verbose = true;
+		// advance args by 1
+		args = args.subspan(1);
 	}
 
 	if (args.empty()) {
+		// print usage
 		std::cout << std::format("usage: {} [-v] \"<expression>\"\n", *argv);
 		return EXIT_SUCCESS;
 	}
 
+	// run kalcy on input expression
 	if (!run(args.front(), verbose)) { return EXIT_FAILURE; }
 
+	// print epilogue
 	std::cout << std::format("\n^^ kalcy v{}\n", kalcy::version_v);
 }