diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2ad72d2..a1d5c5e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,13 +3,15 @@ project(Elna)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS 1)
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 14)
 
-find_package(Boost CONFIG COMPONENTS process program_options REQUIRED)
+# find_package(Boost CONFIG COMPONENTS process program_options REQUIRED)
 find_package(FLEX REQUIRED)
 find_package(BISON REQUIRED)
 
-include_directories(${Boost_INCLUDE_DIR})
+# include_directories(${Boost_INCLUDE_DIR})
+
+link_libraries(stdc++fs)
 
 FLEX_TARGET(lexer source/lexer.ll ${CMAKE_CURRENT_BINARY_DIR}/lexer.cpp)
 BISON_TARGET(parser source/parser.yy ${CMAKE_CURRENT_BINARY_DIR}/parser.cpp)
@@ -22,7 +24,8 @@ add_executable(elna cli/main.cpp
 	source/symbol_table.cpp include/elna/source/symbol_table.hpp
 	source/result.cpp include/elna/source/result.hpp
 	source/semantic.cpp include/elna/source/semantic.hpp
+	cli/cl.cpp include/elna/cli/cl.hpp
 	${BISON_parser_OUTPUTS} ${FLEX_lexer_OUTPUTS}
 )
 target_include_directories(elna PRIVATE ${CMAKE_CURRENT_BINARY_DIR} include)
-target_link_libraries(elna LINK_PUBLIC ${Boost_LIBRARIES})
+# target_link_libraries(elna LINK_PUBLIC ${Boost_LIBRARIES})
diff --git a/cli/cl.cpp b/cli/cl.cpp
new file mode 100644
index 0000000..c27aff5
--- /dev/null
+++ b/cli/cl.cpp
@@ -0,0 +1,43 @@
+#include "elna/cli/cl.hpp"
+#include "elna/source/types.hpp"
+#include <iostream>
+
+namespace elna
+{
+namespace cli
+{
+    void print_error(const std::unique_ptr<source::error>& compile_error)
+    {
+        std::cerr << compile_error->path().string() << ":"
+            << compile_error->line() << ':' << compile_error->column()
+            << ": " << compile_error->what() << std::endl;
+    }
+
+    constexpr std::size_t pointer_size = 4;
+
+    std::shared_ptr<source::symbol_table> add_builtin_symbols()
+    {
+        source::symbol_table result;
+        std::vector<std::shared_ptr<const source::type>> intrinsic_arguments;
+
+        auto boolean_info = std::make_shared<source::type_info>(source::boolean_type);
+        auto int_info = std::make_shared<source::type_info>(source::int_type);
+        result.enter("Boolean", boolean_info);
+        result.enter("Int", int_info);
+
+        intrinsic_arguments.push_back(int_info->type());
+        auto writei = std::make_shared<source::intrinsic_info>(
+                source::procedure_type{ intrinsic_arguments, pointer_size });
+        result.enter("writei", writei);
+        intrinsic_arguments.clear();
+
+        intrinsic_arguments.push_back(boolean_info->type());
+        auto writeb = std::make_shared<source::intrinsic_info>(
+                source::procedure_type{ intrinsic_arguments, pointer_size });
+        result.enter("writeb", writeb);
+        intrinsic_arguments.clear();
+
+        return std::make_shared<source::symbol_table>(std::move(result));
+    }
+}
+}
diff --git a/cli/main.cpp b/cli/main.cpp
index 6da37e7..085ae2f 100644
--- a/cli/main.cpp
+++ b/cli/main.cpp
@@ -1,21 +1,22 @@
 #include <elna/source/driver.hpp>
+#include "elna/source/semantic.hpp"
+#include "elna/cli/cl.hpp"
 #include "parser.hpp"
 #include <sstream>
 
+constexpr std::size_t pointer_size = 4;
+
 int main()
 {
     elna::source::driver driver{ "-" };
     std::istringstream inp(R"(
-        const world = 5, hello = 7;
-        var x: int, y: boolean;
+        var x: Int;
 
         proc f();
         begin
-            x := 8
         end;
 
         begin
-            while false do inc(5)
         end.
     )");
 
@@ -33,6 +34,12 @@ int main()
         }
         return result;
     }
+    auto symbol_table = elna::cli::add_builtin_symbols();
+    elna::source::name_analysis_visitor name_analysis_visitor{ symbol_table, "-", pointer_size };
+    elna::source::type_analysis_visitor type_analysis_visitor{ symbol_table, "-", pointer_size };
+
+    name_analysis_visitor.visit(driver.tree.get());
+
     for (auto& definition : driver.tree->definitions())
     {
         if (auto const_definition = dynamic_cast<elna::source::constant_definition *>(definition.get()))
diff --git a/include/elna/cli/cl.hpp b/include/elna/cli/cl.hpp
new file mode 100644
index 0000000..9943304
--- /dev/null
+++ b/include/elna/cli/cl.hpp
@@ -0,0 +1,37 @@
+#pragma once
+
+#include <algorithm>
+#include "elna/source/symbol_table.hpp"
+#include "elna/source/result.hpp"
+
+namespace elna
+{
+namespace cli
+{
+    /**
+     * Formats and prints the given error.
+     *
+     * \param compile_error The error to print.
+     */
+    void print_error(const std::unique_ptr<source::error>& compile_error);
+
+    /**
+     * Prints the given errors to the standard output.
+     *
+     * \param begin Pointer to the first error.
+     * \param end Pointer pass the last error.
+     */
+    template<typename I>
+    void print_errors(I begin, I end)
+    {
+        std::for_each(begin, end, &print_error);
+    }
+
+    /**
+     * Creates a symbol table with predefined symbols.
+     *
+     * \return A symbol table with predefined symbols.
+     */
+    std::shared_ptr<source::symbol_table> add_builtin_symbols();
+}
+}
diff --git a/include/elna/source/ast.hpp b/include/elna/source/ast.hpp
index c58effb..7fa0681 100644
--- a/include/elna/source/ast.hpp
+++ b/include/elna/source/ast.hpp
@@ -4,7 +4,9 @@
 #include "elna/source/result.hpp"
 #include "elna/source/types.hpp"
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     enum class binary_operator
     {
@@ -481,3 +483,4 @@ namespace elna::source
         unary_operator operation() const noexcept;
     };
 }
+}
diff --git a/include/elna/source/driver.hpp b/include/elna/source/driver.hpp
index e91938f..f1b99fd 100644
--- a/include/elna/source/driver.hpp
+++ b/include/elna/source/driver.hpp
@@ -4,7 +4,9 @@
 #include "elna/source/ast.hpp"
 #include "location.hh"
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     position make_position(const yy::location& location);
 
@@ -14,7 +16,7 @@ namespace elna::source
 
     public:
         syntax_error(const std::string& message,
-                const std::filesystem::path& input_file, const yy::location& location);
+                const std::experimental::filesystem::path& input_file, const yy::location& location);
 
         virtual std::string what() const override;
     };
@@ -22,14 +24,15 @@ namespace elna::source
     class driver
     {
         std::list<std::unique_ptr<struct error>> m_errors;
-        const std::filesystem::path input_file;
+        const std::experimental::filesystem::path input_file;
 
     public:
         std::unique_ptr<program> tree;
 
-        driver(const std::filesystem::path& input_file);
+        driver(const std::experimental::filesystem::path& input_file);
 
         void error(const yy::location& loc, const std::string& message);
         const std::list<std::unique_ptr<struct error>>& errors() const noexcept;
     };
 }
+}
diff --git a/include/elna/source/result.hpp b/include/elna/source/result.hpp
index 2dc9a69..0063fe4 100644
--- a/include/elna/source/result.hpp
+++ b/include/elna/source/result.hpp
@@ -1,10 +1,12 @@
 #pragma once
 
 #include <cstddef>
-#include <filesystem>
+#include <experimental/filesystem>
 #include "elna/source/types.hpp"
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     /**
      * Position in the source text.
@@ -24,7 +26,7 @@ namespace elna::source
     class error
     {
         position m_position;
-        std::filesystem::path m_path;
+        std::experimental::filesystem::path m_path;
 
     protected:
         /**
@@ -33,7 +35,7 @@ namespace elna::source
          * \param path Source file name.
          * \param position Error position in the source text.
          */
-        error(const std::filesystem::path& path, const position position);
+        error(const std::experimental::filesystem::path& path, const position position);
 
     public:
         virtual ~error() noexcept = default;
@@ -48,7 +50,7 @@ namespace elna::source
         std::size_t column() const noexcept;
 
         /// Source file name.
-        const std::filesystem::path& path() const noexcept;
+        const std::experimental::filesystem::path& path() const noexcept;
     };
 
     class name_collision final : public error
@@ -63,7 +65,7 @@ namespace elna::source
          * \param current Current symbol position.
          * \param previous Position of the previously defined symbol.
          */
-        name_collision(const std::string& name, const std::filesystem::path& path,
+        name_collision(const std::string& name, const std::experimental::filesystem::path& path,
                 const position current, const position previous);
 
         std::string what() const override;
@@ -90,7 +92,7 @@ namespace elna::source
          * \param path Source file name.
          * \param position Operation position.
          */
-        type_mismatch(std::shared_ptr<const type> got, operation kind, const std::filesystem::path& path,
+        type_mismatch(std::shared_ptr<const type> got, operation kind, const std::experimental::filesystem::path& path,
                 const struct position position);
 
         std::string what() const override;
@@ -100,3 +102,4 @@ namespace elna::source
         operation kind;
     };
 }
+}
diff --git a/include/elna/source/semantic.hpp b/include/elna/source/semantic.hpp
index 752c596..12210db 100644
--- a/include/elna/source/semantic.hpp
+++ b/include/elna/source/semantic.hpp
@@ -4,12 +4,14 @@
 #include "elna/source/ast.hpp"
 #include "elna/source/symbol_table.hpp"
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     class name_analysis_visitor final : public empty_visitor
     {
         std::shared_ptr<symbol_table> table;
-        const std::filesystem::path filename;
+        const std::experimental::filesystem::path filename;
         std::list<std::unique_ptr<error>> m_errors;
         const std::size_t pointer_size;
 
@@ -21,7 +23,7 @@ namespace elna::source
          * \param path Source filename.
          * \param target_pointer_size Pointer size on the target platform.
          */
-        name_analysis_visitor(std::shared_ptr<symbol_table> table, const std::filesystem::path& filename,
+        name_analysis_visitor(std::shared_ptr<symbol_table> table, const std::experimental::filesystem::path& filename,
                 const std::size_t target_pointer_size);
 
         /**
@@ -60,7 +62,7 @@ namespace elna::source
     class type_analysis_visitor final : public empty_visitor
     {
         std::shared_ptr<symbol_table> table;
-        const std::filesystem::path filename;
+        const std::experimental::filesystem::path filename;
         const std::size_t pointer_size;
         std::list<std::unique_ptr<error>> m_errors;
 
@@ -70,7 +72,7 @@ namespace elna::source
          * \param path Source filename.
          * \param target_pointer_size Pointer size on the target platform.
          */
-        type_analysis_visitor(std::shared_ptr<symbol_table> table, const std::filesystem::path& filename,
+        type_analysis_visitor(std::shared_ptr<symbol_table> table, const std::experimental::filesystem::path& filename,
                 const std::size_t target_pointer_size);
 
         /**
@@ -92,3 +94,4 @@ namespace elna::source
         void visit(assign_statement *statement) override;
     };
 }
+}
diff --git a/include/elna/source/symbol_table.hpp b/include/elna/source/symbol_table.hpp
index f0eb9fa..6e4ef9a 100644
--- a/include/elna/source/symbol_table.hpp
+++ b/include/elna/source/symbol_table.hpp
@@ -5,7 +5,9 @@
 #include <string>
 #include <memory>
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     class symbol_table;
 
@@ -159,3 +161,4 @@ namespace elna::source
         std::shared_ptr<symbol_table> scope();
     };
 }
+}
diff --git a/include/elna/source/types.hpp b/include/elna/source/types.hpp
index 917ddda..d002f18 100644
--- a/include/elna/source/types.hpp
+++ b/include/elna/source/types.hpp
@@ -4,7 +4,9 @@
 #include <string>
 #include <vector>
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     /**
      * Type representation.
@@ -94,6 +96,7 @@ namespace elna::source
     bool operator==(const type& lhs, const type& rhs) noexcept;
     bool operator!=(const type& lhs, const type& rhs) noexcept;
 
-    inline const primitive_type boolean_type{ "Boolean", 1 };
-    inline const primitive_type int_type{ "Int", 4 };
+    extern const primitive_type boolean_type;
+    extern const primitive_type int_type;
+}
 }
diff --git a/source/ast.cpp b/source/ast.cpp
index c6871df..c258549 100644
--- a/source/ast.cpp
+++ b/source/ast.cpp
@@ -1,7 +1,9 @@
 #include "elna/source/ast.hpp"
 #include <stdexcept>
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     void empty_visitor::visit(declaration *declaration)
     {
@@ -522,3 +524,4 @@ namespace elna::source
         return *m_body;
     }
 }
+}
diff --git a/source/driver.cpp b/source/driver.cpp
index a83ea8b..d1355ca 100644
--- a/source/driver.cpp
+++ b/source/driver.cpp
@@ -1,6 +1,8 @@
 #include "elna/source/driver.hpp"
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     position make_position(const yy::location& location)
     {
@@ -11,7 +13,7 @@ namespace elna::source
     }
 
     syntax_error::syntax_error(const std::string& message,
-            const std::filesystem::path& input_file, const yy::location& location)
+            const std::experimental::filesystem::path& input_file, const yy::location& location)
         : error(input_file, make_position(location)), message(message)
     {
     }
@@ -21,7 +23,7 @@ namespace elna::source
         return message;
     }
 
-    driver::driver(const std::filesystem::path& input_file)
+    driver::driver(const std::experimental::filesystem::path& input_file)
         : input_file(input_file)
     {
     }
@@ -36,3 +38,4 @@ namespace elna::source
         return m_errors;
     }
 }
+}
diff --git a/source/result.cpp b/source/result.cpp
index f79e85f..2362d2b 100644
--- a/source/result.cpp
+++ b/source/result.cpp
@@ -1,8 +1,10 @@
 #include "elna/source/result.hpp"
 
-namespace elna::source
+namespace elna
 {
-    error::error(const std::filesystem::path& path, const position position)
+namespace source
+{
+    error::error(const std::experimental::filesystem::path& path, const position position)
         : m_position(position), m_path(path)
     {
     }
@@ -17,12 +19,12 @@ namespace elna::source
         return this->m_position.column;
     }
 
-    const std::filesystem::path& error::path() const noexcept
+    const std::experimental::filesystem::path& error::path() const noexcept
     {
         return this->m_path;
     }
 
-    name_collision::name_collision(const std::string& name, const std::filesystem::path& path,
+    name_collision::name_collision(const std::string& name, const std::experimental::filesystem::path& path,
             const position current, const position previous)
         : error(path, current), name(name), previous(previous)
     {
@@ -33,8 +35,8 @@ namespace elna::source
         return "Name '" + name + "' was already defined";
     }
 
-    type_mismatch::type_mismatch(std::shared_ptr<const type> got, operation kind, const std::filesystem::path& path,
-            const struct position position)
+    type_mismatch::type_mismatch(std::shared_ptr<const type> got, operation kind,
+            const std::experimental::filesystem::path& path, const struct position position)
         : error(path, position), kind(kind), got(got)
     {
     }
@@ -44,3 +46,4 @@ namespace elna::source
         return "Type cannot be used here.";
     }
 }
+}
diff --git a/source/semantic.cpp b/source/semantic.cpp
index 789fd48..6734a01 100644
--- a/source/semantic.cpp
+++ b/source/semantic.cpp
@@ -2,10 +2,12 @@
 #include "elna/source/result.hpp"
 #include <cstdlib>
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     name_analysis_visitor::name_analysis_visitor(std::shared_ptr<symbol_table> table,
-            const std::filesystem::path& filename, const std::size_t target_pointer_size)
+            const std::experimental::filesystem::path& filename, const std::size_t target_pointer_size)
         : table(table), filename(filename), pointer_size(target_pointer_size)
     {
     }
@@ -33,11 +35,11 @@ namespace elna::source
         }
     }
 
-    void name_analysis_visitor::visit(declaration *declaration)
+    void name_analysis_visitor::visit(declaration *declarationx)
     {
-        std::shared_ptr<const type> declaration_type = convert_declaration_type(declaration->type());
+        std::shared_ptr<const type> declaration_type = convert_declaration_type(declarationx->type());
 
-        this->table->enter(declaration->identifier(),
+        this->table->enter(declarationx->identifier(),
                 std::make_shared<variable_info>(declaration_type));
     }
 
@@ -132,7 +134,7 @@ namespace elna::source
     }
 
     type_analysis_visitor::type_analysis_visitor(std::shared_ptr<symbol_table> table,
-            const std::filesystem::path& filename, const std::size_t target_pointer_size)
+            const std::experimental::filesystem::path& filename, const std::size_t target_pointer_size)
         : table(table), filename(filename), pointer_size(target_pointer_size)
     {
     }
@@ -323,3 +325,4 @@ namespace elna::source
         return m_errors;
     }
 }
+}
diff --git a/source/symbol_table.cpp b/source/symbol_table.cpp
index 8801fa7..d404ccb 100644
--- a/source/symbol_table.cpp
+++ b/source/symbol_table.cpp
@@ -1,7 +1,9 @@
 #include "elna/source/types.hpp"
 #include "elna/source/symbol_table.hpp"
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     symbol_table::symbol_table(std::shared_ptr<symbol_table> scope)
         : outer_scope(scope)
@@ -25,7 +27,7 @@ namespace elna::source
 
     void symbol_table::enter(const std::string& name, std::shared_ptr<info> entry)
     {
-        entries.insert_or_assign(name, entry);
+        entries.insert({ name, entry });
     }
 
     std::shared_ptr<symbol_table> symbol_table::scope()
@@ -127,3 +129,4 @@ namespace elna::source
         return local_stack_size + argument_stack_size;
     }
 }
+}
diff --git a/source/types.cpp b/source/types.cpp
index dbc96a9..b99685e 100644
--- a/source/types.cpp
+++ b/source/types.cpp
@@ -1,6 +1,8 @@
 #include <elna/source/types.hpp>
 
-namespace elna::source
+namespace elna
+{
+namespace source
 {
     type::type(const std::size_t byte_size)
         : byte_size(byte_size)
@@ -93,4 +95,8 @@ namespace elna::source
     {
         return !(lhs == rhs);
     }
+
+    const primitive_type boolean_type{ "Boolean", 1 };
+    const primitive_type int_type{ "Int", 4 };
+}
 }