Meta+Env: Fix count on nil value

CMakeLists.txt

@@ -95,3 +95,7 @@ add_dependencies(test2 ${PROJECT})
 add_custom_target(test3
     COMMAND env STEP=step_env MAL_IMPL=js ../vendor/mal/runtest.py --deferrable --optional ../vendor/mal/tests/step3_env.mal -- ./${PROJECT})
 add_dependencies(test3 ${PROJECT})
+
+add_custom_target(test4
+    COMMAND env STEP=step_env MAL_IMPL=js ../vendor/mal/runtest.py --deferrable --optional ../vendor/mal/tests/step4_if_fn_do.mal -- ./${PROJECT})
+add_dependencies(test4 ${PROJECT})

src/ast.h

@@ -8,13 +8,13 @@
 
 #include <cstdint>    // int64_t, uint8_t
 #include <functional> // std::function
+#include <list>
 #include <memory> // std::shared_ptr
 #include <span>
 #include <string>
 #include <string_view>
 #include <typeinfo> // typeid
 #include <unordered_map>
-#include <vector>
 
 #include "ruc/format/formatter.h"
 
@@ -33,9 +33,9 @@ public:
 	bool fastIs() const = delete;
 
 	virtual bool isCollection() const { return false; }
+	virtual bool isList() const { return false; }
 	virtual bool isVector() const { return false; }
 	virtual bool isHashMap() const { return false; }
-	virtual bool isList() const { return false; }
 	virtual bool isString() const { return false; }
 	virtual bool isKeyword() const { return false; }
 	virtual bool isNumber() const { return false; }
@@ -57,7 +57,7 @@ public:
 
 	void addNode(ASTNodePtr node);
 
-	const std::vector<ASTNodePtr>& nodes() const { return m_nodes; }
+	const std::list<ASTNodePtr>& nodes() const { return m_nodes; }
 	size_t size() const { return m_nodes.size(); }
 	bool empty() const { return m_nodes.size() == 0; }
 
@@ -65,7 +65,7 @@ protected:
 	Collection() {}
 
 private:
-	std::vector<ASTNodePtr> m_nodes;
+	std::list<ASTNodePtr> m_nodes;
 };
 
 // -----------------------------------------
@@ -161,22 +161,6 @@ private:
 
 // -----------------------------------------
 
-// Symbols
-class Symbol final : public ASTNode {
-public:
-	explicit Symbol(const std::string& symbol);
-	virtual ~Symbol() = default;
-
-	virtual bool isSymbol() const override { return true; }
-
-	const std::string& symbol() const { return m_symbol; }
-
-private:
-	std::string m_symbol;
-};
-
-// -----------------------------------------
-
 // true, false, nil
 class Value final : public ASTNode {
 public:
@@ -199,7 +183,23 @@ private:
 
 // -----------------------------------------
 
-using Lambda = std::function<ASTNodePtr(std::span<ASTNodePtr>)>;
+// Symbols
+class Symbol final : public ASTNode {
+public:
+	explicit Symbol(const std::string& symbol);
+	virtual ~Symbol() = default;
+
+	virtual bool isSymbol() const override { return true; }
+
+	const std::string& symbol() const { return m_symbol; }
+
+private:
+	std::string m_symbol;
+};
+
+// -----------------------------------------
+
+using Lambda = std::function<ASTNodePtr(std::list<ASTNodePtr>)>;
 
 class Function final : public ASTNode {
 public:
@@ -247,10 +247,10 @@ template<>
 inline bool ASTNode::fastIs<Number>() const { return isNumber(); }
 
 template<>
-inline bool ASTNode::fastIs<Symbol>() const { return isSymbol(); }
+inline bool ASTNode::fastIs<Value>() const { return isValue(); }
 
 template<>
-inline bool ASTNode::fastIs<Value>() const { return isValue(); }
+inline bool ASTNode::fastIs<Symbol>() const { return isSymbol(); }
 
 template<>
 inline bool ASTNode::fastIs<Function>() const { return isFunction(); }

src/environment.cpp

@@ -64,9 +64,16 @@ GlobalEnvironment::GlobalEnvironment()
 	gte();
 
 	list();
-	is_list();
-	is_empty();
+	isList();
+	isEmpty();
 	count();
+
+	str();
+	prStr();
+	prn();
+	println();
+
+	equal();
 }
 
 } // namespace blaze

src/environment.h

@@ -49,11 +49,16 @@ private:
 	void gte(); // >=
 
 	void list();    // list
-	void is_list();  // list?
-	void is_empty(); // empty?
+	void isList();  // list?
+	void isEmpty(); // empty?
 	void count();   // count
 
-	// void equal(); // =
+	void str();     // str
+	void prStr();   // pr-str
+	void prn();     // prn
+	void println(); // println
+
+	void equal(); // =
 };
 
 } // namespace blaze

src/eval.cpp

@@ -4,10 +4,11 @@
  * SPDX-License-Identifier: MIT
  */
 
+#include <iterator> // sd::advance, std::next, std::prev
+#include <list>
 #include <memory> // std::static_pointer_cast
 #include <span>   // std::span
 #include <string>
-#include <vector>
 
 #include "ast.h"
 #include "environment.h"
@@ -47,14 +48,21 @@ ASTNodePtr Eval::evalImpl(ASTNodePtr ast, EnvironmentPtr env)
 
 	// Environment
 	auto nodes = list->nodes();
-	if (is<Symbol>(nodes[0].get())) {
-		auto symbol = std::static_pointer_cast<Symbol>(nodes[0])->symbol();
+	if (is<Symbol>(nodes.front().get())) {
+		auto symbol = std::static_pointer_cast<Symbol>(nodes.front())->symbol();
+		nodes.pop_front();
 		if (symbol == "def!") {
 			return evalDef(nodes, env);
 		}
 		if (symbol == "let*") {
 			return evalLet(nodes, env);
 		}
+		if (symbol == "do") {
+			return evalDo(nodes, env);
+		}
+		if (symbol == "if") {
+			return evalIf(nodes, env);
+		}
 	}
 
 	// Function call
@@ -116,21 +124,24 @@ ASTNodePtr Eval::evalAst(ASTNodePtr ast, EnvironmentPtr env)
 	return ast;
 }
 
-ASTNodePtr Eval::evalDef(const std::vector<ASTNodePtr>& nodes, EnvironmentPtr env)
+ASTNodePtr Eval::evalDef(const std::list<ASTNodePtr>& nodes, EnvironmentPtr env)
 {
-	if (nodes.size() != 3) {
-		Error::the().addError(format("wrong number of arguments: def!, {}", nodes.size() - 1));
+	if (nodes.size() != 2) {
+		Error::the().addError(format("wrong number of arguments: def!, {}", nodes.size()));
 		return nullptr;
 	}
 
+	auto first_argument = *nodes.begin();
+	auto second_argument = *std::next(nodes.begin());
+
 	// First element needs to be a Symbol
-	if (!is<Symbol>(nodes[1].get())) {
-		Error::the().addError(format("wrong type argument: symbol, {}", nodes[1]));
+	if (!is<Symbol>(first_argument.get())) {
+		Error::the().addError(format("wrong type argument: symbol, {}", first_argument));
 		return nullptr;
 	}
 
-	std::string symbol = std::static_pointer_cast<Symbol>(nodes[1])->symbol();
-	ASTNodePtr value = evalImpl(nodes[2], env);
+	std::string symbol = std::static_pointer_cast<Symbol>(first_argument)->symbol();
+	ASTNodePtr value = evalImpl(second_argument, env);
 
 	// Dont overwrite symbols after an error
 	if (Error::the().hasAnyError()) {
@@ -141,27 +152,30 @@ ASTNodePtr Eval::evalDef(const std::vector<ASTNodePtr>& nodes, EnvironmentPtr en
 	return env->set(symbol, value);
 }
 
-ASTNodePtr Eval::evalLet(const std::vector<ASTNodePtr>& nodes, EnvironmentPtr env)
+ASTNodePtr Eval::evalLet(const std::list<ASTNodePtr>& nodes, EnvironmentPtr env)
 {
-	if (nodes.size() != 3) {
-		Error::the().addError(format("wrong number of arguments: let*, {}", nodes.size() - 1));
+	if (nodes.size() != 2) {
+		Error::the().addError(format("wrong number of arguments: let*, {}", nodes.size()));
 		return nullptr;
 	}
 
+	auto first_argument = *nodes.begin();
+	auto second_argument = *std::next(nodes.begin());
+
 	// First argument needs to be a List or Vector
-	if (!is<List>(nodes[1].get()) && !is<Vector>(nodes[1].get())) {
-		Error::the().addError(format("wrong argument type: list, '{}'", nodes[1]));
+	if (!is<List>(first_argument.get()) && !is<Vector>(first_argument.get())) {
+		Error::the().addError(format("wrong argument type: list, '{}'", first_argument));
 		return nullptr;
 	}
 
 	// Get the nodes out of the List or Vector
-	std::vector<ASTNodePtr> binding_nodes;
-	if (is<List>(nodes[1].get())) {
-		auto bindings = std::static_pointer_cast<List>(nodes[1]);
+	std::list<ASTNodePtr> binding_nodes;
+	if (is<List>(first_argument.get())) {
+		auto bindings = std::static_pointer_cast<List>(first_argument);
 		binding_nodes = bindings->nodes();
 	}
 	else {
-		auto bindings = std::static_pointer_cast<Vector>(nodes[1]);
+		auto bindings = std::static_pointer_cast<Vector>(first_argument);
 		binding_nodes = bindings->nodes();
 	}
 
@@ -175,21 +189,58 @@ ASTNodePtr Eval::evalLet(const std::vector<ASTNodePtr>& nodes, EnvironmentPtr en
 	// Create new environment
 	auto let_env = makePtr<Environment>(env);
 
-	for (size_t i = 0; i < count; i += 2) {
+	for (auto it = binding_nodes.begin(); it != binding_nodes.end(); std::advance(it, 2)) {
 		// First element needs to be a Symbol
-		if (!is<Symbol>(binding_nodes[i].get())) {
-			Error::the().addError(format("wrong argument type: symbol, '{}'", binding_nodes[i]));
+		if (!is<Symbol>(*it->get())) {
+			Error::the().addError(format("wrong argument type: symbol, '{}'", *it));
 			return nullptr;
 		}
 
-		std::string key = std::static_pointer_cast<Symbol>(binding_nodes[i])->symbol();
-		ASTNodePtr value = evalImpl(binding_nodes[i + 1], let_env);
+		std::string key = std::static_pointer_cast<Symbol>(*it)->symbol();
+		ASTNodePtr value = evalImpl(*std::next(it), let_env);
 		let_env->set(key, value);
 	}
 
 	// TODO: Remove limitation of 3 arguments
 	//       Eval all values in this new env, return last sexp of the result
-	return evalImpl(nodes[2], let_env);
+	return evalImpl(second_argument, let_env);
+}
+
+ASTNodePtr Eval::evalDo(const std::list<ASTNodePtr>& nodes, EnvironmentPtr env)
+{
+	if (nodes.size() == 0) {
+		Error::the().addError(format("wrong number of arguments: do, {}", nodes.size()));
+		return nullptr;
+	}
+
+	// Evaluate all nodes except the last
+	for (auto it = nodes.begin(); it != std::prev(nodes.end(), 1); ++it) {
+		evalImpl(*it, env);
+	}
+
+	// Eval and return last node
+	return evalImpl(nodes.back(), env);
+}
+
+ASTNodePtr Eval::evalIf(const std::list<ASTNodePtr>& nodes, EnvironmentPtr env)
+{
+	if (nodes.size() != 2 && nodes.size() != 3) {
+		Error::the().addError(format("wrong number of arguments: if, {}", nodes.size()));
+		return nullptr;
+	}
+
+	auto first_argument = *nodes.begin();
+	auto second_argument = *std::next(nodes.begin());
+	auto third_argument = (nodes.size() == 3) ? *std::next(std::next(nodes.begin())) : makePtr<Value>(Value::Nil);
+
+	auto first_evaluated = evalImpl(first_argument, env);
+	if (!is<Value>(first_evaluated.get())
+	    || std::static_pointer_cast<Value>(first_evaluated)->state() == Value::True) {
+		return evalImpl(second_argument, env);
+	}
+	else {
+		return evalImpl(third_argument, env);
+	}
 }
 
 ASTNodePtr Eval::apply(std::shared_ptr<List> evaluated_list)
@@ -200,17 +251,17 @@ ASTNodePtr Eval::apply(std::shared_ptr<List> evaluated_list)
 
 	auto nodes = evaluated_list->nodes();
 
-	if (!is<Function>(nodes[0].get())) {
-		Error::the().addError(format("invalid function: {}", nodes[0]));
+	if (!is<Function>(nodes.front().get())) {
+		Error::the().addError(format("invalid function: {}", nodes.front()));
 		return nullptr;
 	}
 
 	// car
-	auto lambda = std::static_pointer_cast<Function>(nodes[0])->lambda();
+	auto lambda = std::static_pointer_cast<Function>(nodes.front())->lambda();
 	// cdr
-	std::span<ASTNodePtr> span { nodes.data() + 1, nodes.size() - 1 };
+	nodes.pop_front();
 
-	return lambda(span);
+	return lambda(nodes);
 }
 
 } // namespace blaze

src/eval.h

@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <vector>
+#include <list>
 
 #include "ast.h"
 #include "environment.h"
@@ -25,8 +25,10 @@ public:
 private:
 	ASTNodePtr evalImpl(ASTNodePtr ast, EnvironmentPtr env);
 	ASTNodePtr evalAst(ASTNodePtr ast, EnvironmentPtr env);
-	ASTNodePtr evalDef(const std::vector<ASTNodePtr>& nodes, EnvironmentPtr env);
-	ASTNodePtr evalLet(const std::vector<ASTNodePtr>& nodes, EnvironmentPtr env);
+	ASTNodePtr evalDef(const std::list<ASTNodePtr>& nodes, EnvironmentPtr env);
+	ASTNodePtr evalLet(const std::list<ASTNodePtr>& nodes, EnvironmentPtr env);
+	ASTNodePtr evalDo(const std::list<ASTNodePtr>& nodes, EnvironmentPtr env);
+	ASTNodePtr evalIf(const std::list<ASTNodePtr>& nodes, EnvironmentPtr env);
 	ASTNodePtr apply(std::shared_ptr<List> evaluated_list);
 
 	ASTNodePtr m_ast;

src/functions.cpp

@@ -5,19 +5,23 @@
  */
 
 #include <memory> // std::static_pointer_cast
+#include <string>
 
+#include "ruc/format/color.h"
 #include "ruc/format/format.h"
 
 #include "ast.h"
 #include "environment.h"
 #include "error.h"
+#include "printer.h"
 #include "types.h"
+#include "util.h"
 
 namespace blaze {
 
 void GlobalEnvironment::add()
 {
-	auto add = [](std::span<ASTNodePtr> nodes) -> ASTNodePtr {
+	auto add = [](std::list<ASTNodePtr> nodes) -> ASTNodePtr {
 		int64_t result = 0;
 
 		for (auto node : nodes) {
@@ -37,7 +41,7 @@ void GlobalEnvironment::add()
 
 void GlobalEnvironment::sub()
 {
-	auto sub = [](std::span<ASTNodePtr> nodes) -> ASTNodePtr {
+	auto sub = [](std::list<ASTNodePtr> nodes) -> ASTNodePtr {
 		if (nodes.size() == 0) {
 			return makePtr<Number>(0);
 		}
@@ -50,7 +54,7 @@ void GlobalEnvironment::sub()
 		}
 
 		// Start with the first number
-		int64_t result = std::static_pointer_cast<Number>(nodes[0])->number();
+		int64_t result = std::static_pointer_cast<Number>(nodes.front())->number();
 
 		// Skip the first node
 		for (auto it = std::next(nodes.begin()); it != nodes.end(); ++it) {
@@ -65,7 +69,7 @@ void GlobalEnvironment::sub()
 
 void GlobalEnvironment::mul()
 {
-	auto mul = [](std::span<ASTNodePtr> nodes) -> ASTNodePtr {
+	auto mul = [](std::list<ASTNodePtr> nodes) -> ASTNodePtr {
 		int64_t result = 1;
 
 		for (auto node : nodes) {
@@ -85,7 +89,7 @@ void GlobalEnvironment::mul()
 
 void GlobalEnvironment::div()
 {
-	auto div = [this](std::span<ASTNodePtr> nodes) -> ASTNodePtr {
+	auto div = [this](std::list<ASTNodePtr> nodes) -> ASTNodePtr {
 		if (nodes.size() == 0) {
 			Error::the().addError(format("wrong number of arguments: {}, 0", m_current_key));
 			return nullptr;
@@ -99,7 +103,7 @@ void GlobalEnvironment::div()
 		}
 
 		// Start with the first number
-		double result = std::static_pointer_cast<Number>(nodes[0])->number();
+		double result = std::static_pointer_cast<Number>(nodes.front())->number();
 
 		// Skip the first node
 		for (auto it = std::next(nodes.begin()); it != nodes.end(); ++it) {
@@ -115,7 +119,7 @@ void GlobalEnvironment::div()
 // -----------------------------------------
 
 #define NUMBER_COMPARE(symbol, comparison_symbol)                                                                \
-	auto lambda = [this](std::span<ASTNodePtr> nodes) -> ASTNodePtr {                                            \
+	auto lambda = [this](std::list<ASTNodePtr> nodes) -> ASTNodePtr {                                            \
 		bool result = true;                                                                                      \
                                                                                                                  \
 		if (nodes.size() < 2) {                                                                                  \
@@ -131,7 +135,7 @@ void GlobalEnvironment::div()
 		}                                                                                                        \
                                                                                                                  \
 		/* Start with the first number */                                                                        \
-		int64_t number = std::static_pointer_cast<Number>(nodes[0])->number();                                   \
+		int64_t number = std::static_pointer_cast<Number>(nodes.front())->number();                              \
                                                                                                                  \
 		/* Skip the first node */                                                                                \
 		for (auto it = std::next(nodes.begin()); it != nodes.end(); ++it) {                                      \
@@ -172,7 +176,7 @@ void GlobalEnvironment::gte()
 
 void GlobalEnvironment::list()
 {
-	auto list = [](std::span<ASTNodePtr> nodes) -> ASTNodePtr {
+	auto list = [](std::list<ASTNodePtr> nodes) -> ASTNodePtr {
 		auto list = makePtr<List>();
 
 		for (auto node : nodes) {
@@ -185,9 +189,9 @@ void GlobalEnvironment::list()
 	m_values.emplace("list", makePtr<Function>(list));
 }
 
-void GlobalEnvironment::is_list()
+void GlobalEnvironment::isList()
 {
-	auto is_list = [](std::span<ASTNodePtr> nodes) -> ASTNodePtr {
+	auto is_list = [](std::list<ASTNodePtr> nodes) -> ASTNodePtr {
 		bool result = true;
 
 		for (auto node : nodes) {
@@ -203,9 +207,9 @@ void GlobalEnvironment::is_list()
 	m_values.emplace("list?", makePtr<Function>(is_list));
 }
 
-void GlobalEnvironment::is_empty()
+void GlobalEnvironment::isEmpty()
 {
-	auto is_empty = [](std::span<ASTNodePtr> nodes) -> ASTNodePtr {
+	auto is_empty = [](std::list<ASTNodePtr> nodes) -> ASTNodePtr {
 		bool result = true;
 
 		for (auto node : nodes) {
@@ -228,21 +232,25 @@ void GlobalEnvironment::is_empty()
 
 void GlobalEnvironment::count()
 {
-	auto count = [this](std::span<ASTNodePtr> nodes) -> ASTNodePtr {
-		if (nodes.size() > 1) {
+	auto count = [this](std::list<ASTNodePtr> nodes) -> ASTNodePtr {
+		if (nodes.size() != 1) {
 			Error::the().addError(format("wrong number of arguments: {}, {}", m_current_key, nodes.size() - 1));
 			return nullptr;
 		}
 
 		size_t result = 0;
-
-		for (auto node : nodes) {
-			if (!is<List>(node.get())) {
-				Error::the().addError(format("wrong argument type: list, '{}'", node));
-				return nullptr;
+		if (is<Value>(nodes.front().get()) && std::static_pointer_cast<Value>(nodes.front())->state() == Value::Nil) {
+			// result = 0
 		}
-
-			result = std::static_pointer_cast<List>(node)->size();
+		else if (!is<List>(nodes.front().get())) {
+			result = std::static_pointer_cast<List>(nodes.front())->size();
+		}
+		else if (!is<Vector>(nodes.front().get())) {
+			result = std::static_pointer_cast<Vector>(nodes.front())->size();
+		}
+		else {
+			Error::the().addError(format("wrong argument type: list, '{}'", nodes));
+			return nullptr;
 		}
 
 		// FIXME: Add numeric_limits check for implicit cast: size_t > int64_t
@@ -252,4 +260,151 @@ void GlobalEnvironment::count()
 	m_values.emplace("count", makePtr<Function>(count));
 }
 
+// -----------------------------------------
+
+#define PRINTER_STRING(symbol, concatenation, print_readably)                       \
+	auto lambda = [](std::list<ASTNodePtr> nodes) -> ASTNodePtr {                   \
+		std::string result;                                                         \
+                                                                                    \
+		Printer printer;                                                            \
+		for (auto it = nodes.begin(); it != nodes.end(); ++it) {                    \
+			result += format("{}", printer.printNoErrorCheck(*it, print_readably)); \
+                                                                                    \
+			if (!isLast(it, nodes)) {                                               \
+				result += concatenation;                                            \
+			}                                                                       \
+		}                                                                           \
+                                                                                    \
+		return makePtr<String>(result);                                             \
+	};                                                                              \
+                                                                                    \
+	m_values.emplace(symbol, makePtr<Function>(lambda));
+
+void GlobalEnvironment::str()
+{
+	PRINTER_STRING("str", "", false);
+}
+
+void GlobalEnvironment::prStr()
+{
+	PRINTER_STRING("pr-str", " ", true);
+}
+
+#define PRINTER_PRINT(symbol, print_readably)                            \
+	auto lambda = [](std::list<ASTNodePtr> nodes) -> ASTNodePtr {        \
+		Printer printer;                                                 \
+		for (auto it = nodes.begin(); it != nodes.end(); ++it) {         \
+			print("{}", printer.printNoErrorCheck(*it, print_readably)); \
+                                                                         \
+			if (!isLast(it, nodes)) {                                    \
+				print(" ");                                              \
+			}                                                            \
+		}                                                                \
+		print("\n");                                                     \
+                                                                         \
+		return makePtr<Value>(Value::Nil);                               \
+	};                                                                   \
+                                                                         \
+	m_values.emplace(symbol, makePtr<Function>(lambda));
+
+void GlobalEnvironment::prn()
+{
+	PRINTER_PRINT("prn", true);
+}
+
+void GlobalEnvironment::println()
+{
+	PRINTER_PRINT("println", false);
+}
+
+// -----------------------------------------
+
+void GlobalEnvironment::equal()
+{
+	auto lambda = [this](std::list<ASTNodePtr> nodes) -> ASTNodePtr {
+		if (nodes.size() < 2) {
+			Error::the().addError(format("wrong number of arguments: {}, {}", m_current_key, nodes.size() - 1));
+			return nullptr;
+		}
+
+		std::function<bool(ASTNodePtr, ASTNodePtr)> equal =
+			[&equal](ASTNodePtr lhs, ASTNodePtr rhs) -> bool {
+			if ((is<List>(lhs.get()) && is<List>(rhs.get()))
+			    || (is<Vector>(lhs.get()) && is<Vector>(rhs.get()))) {
+				auto lhs_nodes = std::static_pointer_cast<List>(lhs)->nodes();
+				auto rhs_nodes = std::static_pointer_cast<List>(rhs)->nodes();
+
+				if (lhs_nodes.size() != rhs_nodes.size()) {
+					return false;
+				}
+
+				auto lhs_it = lhs_nodes.begin();
+				auto rhs_it = rhs_nodes.begin();
+				for (; lhs_it != lhs_nodes.end(); ++lhs_it, ++rhs_it) {
+					if (!equal(*lhs_it, *rhs_it)) {
+						return false;
+					}
+				}
+
+				return true;
+			}
+
+			if (is<HashMap>(lhs.get()) && is<HashMap>(rhs.get())) {
+				auto lhs_nodes = std::static_pointer_cast<HashMap>(lhs)->elements();
+				auto rhs_nodes = std::static_pointer_cast<HashMap>(rhs)->elements();
+
+				if (lhs_nodes.size() != rhs_nodes.size()) {
+					return false;
+				}
+
+				for (const auto& [key, value] : lhs_nodes) {
+					auto it = rhs_nodes.find(key);
+					if (it == rhs_nodes.end() || !equal(value, it->second)) {
+						return false;
+					}
+				}
+
+				return true;
+			}
+
+			if (is<String>(lhs.get()) && is<String>(rhs.get())
+			    && std::static_pointer_cast<String>(lhs)->data() == std::static_pointer_cast<String>(rhs)->data()) {
+				return true;
+			}
+			if (is<Keyword>(lhs.get()) && is<Keyword>(rhs.get())
+			    && std::static_pointer_cast<Keyword>(lhs)->keyword() == std::static_pointer_cast<Keyword>(rhs)->keyword()) {
+				return true;
+			}
+			if (is<Number>(lhs.get()) && is<Number>(rhs.get())
+			    && std::static_pointer_cast<Number>(lhs)->number() == std::static_pointer_cast<Number>(rhs)->number()) {
+				return true;
+			}
+			if (is<Value>(lhs.get()) && is<Value>(rhs.get())
+			    && std::static_pointer_cast<Value>(lhs)->state() == std::static_pointer_cast<Value>(rhs)->state()) {
+				return true;
+			}
+			if (is<Symbol>(lhs.get()) && is<Symbol>(rhs.get())
+			    && std::static_pointer_cast<Symbol>(lhs)->symbol() == std::static_pointer_cast<Symbol>(rhs)->symbol()) {
+				return true;
+			}
+
+			return false;
+		};
+
+		bool result = true;
+		auto it = nodes.begin();
+		auto it_next = std::next(nodes.begin());
+		for (; it_next != nodes.end(); ++it, ++it_next) {
+			if (!equal(*it, *it_next)) {
+				result = false;
+				break;
+			}
+		}
+
+		return makePtr<Value>((result) ? Value::True : Value::False);
+	};
+
+	m_values.emplace("=", makePtr<Function>(lambda));
+}
+
 } // namespace blaze

src/lexer.cpp

@@ -124,7 +124,7 @@ bool Lexer::consumeSpliceUnquoteOrUnquote()
 bool Lexer::consumeString()
 {
 	size_t column = m_column;
-	std::string text = "\"";
+	std::string text;
 
 	static std::unordered_set<char> exit = {
 		'"',
@@ -134,12 +134,11 @@ bool Lexer::consumeString()
 	};
 
 	bool escape = false;
-	char character = consume();
-	for (;;) {
+	char character = consume(); // "
+	while (true) {
 		character = peek();
 
 		if (!escape && character == '\\') {
-			text += '\\';
 			ignore();
 			escape = true;
 			continue;
@@ -149,16 +148,18 @@ bool Lexer::consumeString()
 			break;
 		}
 
+		if (escape && character == 'n') {
+			text += 0xa; // 10 or \n
+		}
+		else {
 			text += character;
+		}
 		ignore();
 
 		escape = false;
 	}
 
-	if (character == '"') {
-		text += character;
-	}
-	else {
+	if (character != '"') {
 		Error::the().addError({ Token::Type::Error, m_line, column, "expected '\"', got EOF" });
 	}
 
@@ -195,7 +196,7 @@ bool Lexer::consumeKeyword()
 	};
 
 	char character = 0;
-	for (;;) {
+	while (true) {
 		character = peek();
 
 		if (exit.find(character) != exit.end()) {
@@ -238,7 +239,7 @@ bool Lexer::consumeValue()
 	};
 
 	char character = 0;
-	for (;;) {
+	while (true) {
 		character = peek();
 
 		if (exit.find(character) != exit.end()) {
@@ -270,7 +271,7 @@ bool Lexer::consumeComment()
 	};
 
 	char character = 0;
-	for (;;) {
+	while (true) {
 		character = peek();
 
 		if (exit.find(character) != exit.end()) {

src/printer.cpp

@@ -15,6 +15,7 @@
 #include "lexer.h"
 #include "printer.h"
 #include "types.h"
+#include "util.h"
 
 namespace blaze {
 
@@ -28,7 +29,7 @@ Printer::~Printer()
 
 // -----------------------------------------
 
-std::string Printer::print(ASTNodePtr node)
+std::string Printer::print(ASTNodePtr node, bool print_readably)
 {
 	if (Error::the().hasAnyError()) {
 		init();
@@ -36,10 +37,10 @@ std::string Printer::print(ASTNodePtr node)
 		return m_print;
 	}
 
-	return printNoErrorCheck(node);
+	return printNoErrorCheck(node, print_readably);
 }
 
-std::string Printer::printNoErrorCheck(ASTNodePtr node)
+std::string Printer::printNoErrorCheck(ASTNodePtr node, bool print_readably)
 {
 	init();
 
@@ -47,7 +48,7 @@ std::string Printer::printNoErrorCheck(ASTNodePtr node)
 		return {};
 	}
 
-	printImpl(node);
+	printImpl(node, print_readably);
 
 	return m_print;
 }
@@ -61,7 +62,7 @@ void Printer::init()
 	m_print = "";
 }
 
-void Printer::printImpl(ASTNodePtr node)
+void Printer::printImpl(ASTNodePtr node, bool print_readably)
 {
 	auto printSpacing = [this]() -> void {
 		if (!m_first_node && !m_previous_node_is_list) {
@@ -76,8 +77,8 @@ void Printer::printImpl(ASTNodePtr node)
 		m_first_node = false;
 		m_previous_node_is_list = true;
 		auto nodes = std::static_pointer_cast<List>(node)->nodes();
-		for (size_t i = 0; i < nodes.size(); ++i) {
-			printImpl(nodes[i]);
+		for (auto node : nodes) {
+			printImpl(node);
 			m_previous_node_is_list = false;
 		}
 		m_print += ')';
@@ -88,8 +89,8 @@ void Printer::printImpl(ASTNodePtr node)
 		m_first_node = false;
 		m_previous_node_is_list = true;
 		auto nodes = std::static_pointer_cast<Vector>(node)->nodes();
-		for (size_t i = 0; i < nodes.size(); ++i) {
-			printImpl(nodes[i]);
+		for (auto node : nodes) {
+			printImpl(node);
 			m_previous_node_is_list = false;
 		}
 		m_print += ']';
@@ -104,7 +105,7 @@ void Printer::printImpl(ASTNodePtr node)
 			m_print += format("{} ", it->first.front() == 0x7f ? ":" + it->first.substr(1) : it->first); // 127
 			printImpl(it->second);
 
-			if (it != elements.end() && std::next(it) != elements.end()) {
+			if (isLast(it, elements)) {
 				m_print += ' ';
 			}
 		}
@@ -112,9 +113,15 @@ void Printer::printImpl(ASTNodePtr node)
 		m_print += '}';
 	}
 	else if (is<String>(node_raw_ptr)) {
-		// TODO: Implement string readably printing
+		std::string text = std::static_pointer_cast<String>(node)->data();
+		if (print_readably) {
+			text = replaceAll(text, "\\", "\\\\");
+			text = replaceAll(text, "\"", "\\\"");
+			text = replaceAll(text, "\n", "\\n");
+			text = "\"" + text + "\"";
+		}
 		printSpacing();
-		m_print += format("{}", std::static_pointer_cast<String>(node)->data());
+		m_print += format("{}", text);
 	}
 	else if (is<Keyword>(node_raw_ptr)) {
 		printSpacing();

src/printer.h

@@ -17,12 +17,12 @@ public:
 	Printer();
 	virtual ~Printer();
 
-	std::string print(ASTNodePtr node);
-	std::string printNoErrorCheck(ASTNodePtr node);
+	std::string print(ASTNodePtr node, bool print_readably = true);
+	std::string printNoErrorCheck(ASTNodePtr node, bool print_readably = true);
 
 private:
 	void init();
-	void printImpl(ASTNodePtr node);
+	void printImpl(ASTNodePtr node, bool print_readably = true);
 	void printError();
 
 	bool m_first_node { true };

src/reader.cpp

@@ -296,11 +296,6 @@ ASTNodePtr Reader::readString()
 {
 	std::string symbol = consume().symbol;
 
-	// Unbalanced string
-	if (symbol.size() < 2 || symbol.front() != '"' || symbol.back() != '"') {
-		Error::the().addError("expected '\"', got EOF");
-	}
-
 	return makePtr<String>(symbol);
 }
 
@@ -383,15 +378,15 @@ void Reader::dumpImpl(ASTNodePtr node)
 
 	ASTNode* node_raw_ptr = node.get();
 	if (is<List>(node_raw_ptr)) {
-		auto list = std::static_pointer_cast<List>(node);
+		auto nodes = std::static_pointer_cast<List>(node)->nodes();
 		print("{}", indentation);
 		print(fg(ruc::format::TerminalColor::Blue), "ListContainer");
 		print(" <");
 		print(fg(ruc::format::TerminalColor::Blue), "()");
 		print(">\n");
 		m_indentation++;
-		for (size_t i = 0; i < list->nodes().size(); ++i) {
-			dumpImpl(list->nodes()[i]);
+		for (auto node : nodes) {
+			dumpImpl(node);
 		}
 		m_indentation--;
 		return;

src/step4_if_fn_do.cpp

@@ -48,7 +48,7 @@ auto print(blaze::ASTNodePtr exp) -> std::string
 {
 	blaze::Printer printer;
 
-	return printer.print(exp);
+	return printer.print(exp, true);
 }
 
 auto rep(std::string_view input) -> std::string

src/util.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2023 Riyyi
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <string>
+#include <string_view>
+
+namespace blaze {
+
+template<typename It, typename C>
+inline bool isLast(It it, const C& container)
+{
+	return (it != container.end()) && (next(it) == container.end());
+}
+
+inline std::string replaceAll(std::string text, std::string_view search, std::string_view replace)
+{
+	size_t search_length = search.length();
+	size_t replace_length = replace.length();
+	size_t position = text.find(search, 0);
+	while (position != std::string::npos) {
+		text.replace(position, search_length, replace);
+		position += replace_length;
+		position = text.find(search, position);
+	}
+
+	return text;
+}
+
+} // namespace blaze