diff --git a/CMakeLists.txt b/CMakeLists.txt
index d732f0d..961adc9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,6 +5,9 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS 1)
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
 set(CMAKE_CXX_STANDARD 17)
 
+find_package(Boost COMPONENTS program_options REQUIRED)
+include_directories(${Boost_INCLUDE_DIR})
+
 add_executable(tester tests/runner.cpp include/elna/tester.hpp)
 target_include_directories(tester PRIVATE include)
 
@@ -15,7 +18,7 @@ add_executable(elnsh shell/main.cpp
 )
 target_include_directories(elnsh PRIVATE include)
 
-add_library(elna
+add_executable(elna source/main.cpp
 	source/lexer.cpp include/elna/lexer.hpp
 	source/result.cpp include/elna/result.hpp
 	source/riscv.cpp include/elna/riscv.hpp
@@ -24,3 +27,4 @@ add_library(elna
 	source/cl.cpp include/elna/cl.hpp
 )
 target_include_directories(elna PRIVATE include)
+target_link_libraries(elna LINK_PUBLIC ${Boost_LIBRARIES})
diff --git a/Rakefile b/Rakefile
deleted file mode 100644
index 773d560..0000000
--- a/Rakefile
+++ /dev/null
@@ -1,19 +0,0 @@
-require 'pathname'
-require 'rake/clean'
-require 'open3'
-
-DFLAGS = ['--warn-no-deprecated', '-L/usr/lib64/gcc-12']
-BINARY = 'build/bin/elna'
-SOURCES = FileList['source/**/*.d']
-
-directory 'build/riscv'
-
-CLEAN.include 'build'
-CLEAN.include '.dub'
-
-file BINARY => SOURCES do |t|
-  sh({ 'DFLAGS' => (DFLAGS * ' ') }, 'dub', 'build', '--compiler=gdc')
-end
-
-task default: 'build/riscv'
-task default: BINARY
diff --git a/TODO b/TODO
index 6a08d34..fb7f24e 100644
--- a/TODO
+++ b/TODO
@@ -1,4 +1,23 @@
-# Completion
+# Compiler
+
+- Separate headers and sources for the compiler, shell and tests.
+- Make writing ELF independent from the code generation.
+- Argument parsing.
+- Whitespaces are checked twice, in the source class and by lexing.
+- Replace pointer and length with vectors and strings.
+- Choose one name for runner.cpp and tester.hpp.
+- Move argument handling into the cl module.
+- Catch exceptions thrown by the argument parser and print them normally.
+- cmake clean target.
+- Division.
+- Expressions contain one or more terms. Currently it parses another expression on the right side.
+- Multiple factors.
+
+# Shell
+- Persist the history.
+- Replace hard coded ANSI codes with constants or functions.
+
+## Completion
 
 - Configure fzf to show only the current directory files
 - Support multiple selections for insertion in fzf.
@@ -7,17 +26,12 @@
 - Home directory expansion.
 - Show files in the PATH if starting at the beginning of the prompt
 
-# Appearance
+## Appearance
 
 - Add a bar with additional information under the prompt (edit_bar), like the hostname.
 - Show current time in the prompt.
 
-# Input
+## Input
 
 - DEL handling.
 - Starting long running process and killing it with Ctrl-C kills the shell.
-
-# Other
-
-- Persist the history.
-- Replace hard coded ANSI codes with constants or functions.
diff --git a/dub.json b/dub.json
deleted file mode 100644
index 2e76980..0000000
--- a/dub.json
+++ /dev/null
@@ -1,11 +0,0 @@
-{
-	"dependencies": {
-		"tanya": "~>0.19.0"
-	},
-	"name": "elna",
-	"targetType": "executable",
-	"targetPath": "build/bin",
-	"mainSourceFile": "source/main.d",
-	"libs": ["elna", "stdc++"],
-	"lflags": ["-Lbuild"]
-}
diff --git a/include/elna/cl.hpp b/include/elna/cl.hpp
index 36160b4..d431d94 100644
--- a/include/elna/cl.hpp
+++ b/include/elna/cl.hpp
@@ -1,7 +1,9 @@
 #pragma once
 
+#include <filesystem>
+
 namespace elna
 {
     char *readSource(const char *source);
-    int compile(const char *inFile, const char *outputFilename);
+    int compile(const std::filesystem::path& in_file, const std::filesystem::path& out_file);
 }
diff --git a/include/elna/lexer.hpp b/include/elna/lexer.hpp
index 09ab8a6..a6383c9 100644
--- a/include/elna/lexer.hpp
+++ b/include/elna/lexer.hpp
@@ -1,10 +1,13 @@
 #pragma once
 
+#include <cstdint>
 #include <string>
 
 #include "elna/result.hpp"
 
 namespace elna
+{
+namespace lex
 {
     /**
      * Range over the source text that keeps track of the current position.
@@ -14,10 +17,10 @@ namespace elna
         class const_iterator
         {
             std::string::const_iterator m_buffer;
-            Position m_position;
+            elna::source::position m_position;
 
             const_iterator(std::string::const_iterator buffer,
-                    const Position position = Position());
+                    const elna::source::position start_position = elna::source::position());
 
         public:
             using iterator_category = std::forward_iterator_tag;
@@ -26,7 +29,7 @@ namespace elna
             using pointer = const value_type *;
             using reference = const value_type&;
 
-            const Position& position() const noexcept;
+            const elna::source::position& position() const noexcept;
 
             reference operator*() const noexcept;
             pointer operator->() const noexcept;
@@ -54,20 +57,21 @@ namespace elna
         /**
          * Token type.
          */
-        enum Type : std::uint16_t
+        enum class type : std::uint16_t
         {
-            TOKEN_NUMBER = 0,
-            TOKEN_OPERATOR = 1,
-            TOKEN_LET = 2,
-            TOKEN_IDENTIFIER = 3,
-            TOKEN_EQUALS = 4,
-            TOKEN_VAR = 5,
-            TOKEN_SEMICOLON = 6,
-            TOKEN_LEFT_PAREN = 7,
-            TOKEN_RIGHT_PAREN = 8,
-            TOKEN_BANG = 9,
-            TOKEN_DOT = 10,
-            TOKEN_COMMA = 11,
+            number = 0,
+            term_operator = 1,
+            let = 2,
+            identifier = 3,
+            equals = 4,
+            var = 5,
+            semicolon = 6,
+            left_paren = 7,
+            right_paren = 8,
+            bang = 9,
+            dot = 10,
+            comma = 11,
+            factor_operator = 12,
         };
 
         /**
@@ -79,9 +83,9 @@ namespace elna
             const char *identifier;
         };
 
-        Token(Type of, Position position);
-        Token(Type of, std::int32_t value, Position position);
-        Token(Type of, const char *value, Position position);
+        Token(type of, elna::source::position position);
+        Token(type of, std::int32_t value, elna::source::position position);
+        Token(type of, const char *value, elna::source::position position);
         Token(const Token& that);
         Token(Token&& that);
         ~Token();
@@ -89,21 +93,23 @@ namespace elna
         Token& operator=(const Token& that);
         Token& operator=(Token&& that);
 
-        Type of() const noexcept;
+        type of() const noexcept;
         const char *identifier() const noexcept;
         std::int32_t number() const noexcept;
-        const Position& position() const noexcept;
+        const elna::source::position& position() const noexcept;
 
     private:
-        Type m_type;
+        type m_type;
         Value m_value;
-        Position m_position;
+        elna::source::position m_position;
     };
 
     /**
      * Split the source into tokens.
      *
+     * \param buffer Source text.
      * \return Tokens or error.
      */
-    Token *lex(const char *buffer, CompileError *compile_error, std::size_t *length);
+    elna::source::result<std::vector<Token>> lex(const char *buffer);
+}
 }
diff --git a/include/elna/parser.hpp b/include/elna/parser.hpp
index 152aec8..0ee369e 100644
--- a/include/elna/parser.hpp
+++ b/include/elna/parser.hpp
@@ -9,7 +9,9 @@ namespace elna
     enum class BinaryOperator
     {
         sum,
-        subtraction
+        subtraction,
+        multiplication,
+        division
     };
 
     class Node;
@@ -112,12 +114,12 @@ namespace elna
         virtual void accept(ParserVisitor *visitor) override;
     };
 
-    Expression *parseFactor(Token **tokens, std::size_t *length);
-    Expression *parseTerm(Token **tokens, std::size_t *length);
-    Expression *parseExpression(Token **tokens, std::size_t *length);
-    Definition *parseDefinition(Token **tokens, std::size_t *length);
-    Statement *parseStatement(Token **tokens, std::size_t *length);
-    Definition **parseDefinitions(Token **tokens, std::size_t *length, std::size_t *resultLength);
-    Block *parseBlock(Token **tokens, std::size_t *length);
-    Block *parse(Token *tokenStream, std::size_t length);
+    Expression *parseFactor(lex::Token **tokens, std::size_t *length);
+    Expression *parseTerm(lex::Token **tokens, std::size_t *length);
+    Expression *parseExpression(lex::Token **tokens, std::size_t *length);
+    Definition *parseDefinition(lex::Token **tokens, std::size_t *length);
+    Statement *parseStatement(lex::Token **tokens, std::size_t *length);
+    Definition **parseDefinitions(lex::Token **tokens, std::size_t *length, std::size_t *resultLength);
+    Block *parseBlock(lex::Token **tokens, std::size_t *length);
+    Block *parse(lex::Token *tokenStream, std::size_t length);
 }
diff --git a/include/elna/result.hpp b/include/elna/result.hpp
index 5740b62..7e81129 100644
--- a/include/elna/result.hpp
+++ b/include/elna/result.hpp
@@ -1,50 +1,92 @@
 #pragma once
 
 #include <cstddef>
-#include <boost/outcome.hpp>
+#include <variant>
+#include <vector>
+#include <forward_list>
 
 namespace elna
 {
-    /**
-     * Position in the source text.
-     */
-    struct Position
+    namespace source
     {
-        /// Line.
-        std::size_t line = 1;
-
-        /// Column.
-        std::size_t column = 1;
-    };
-
-    /**
-     * A compilation error consists of an error message and position.
-     */
-    struct CompileError
-    {
-    private:
-        char const *message;
-        Position position;
-
-    public:
         /**
-         * @param message Error text.
-         * @param position Error position in the source text.
+         * Position in the source text.
          */
-        CompileError(char const *message, const Position position) noexcept;
+        struct position
+        {
+            /// Line.
+            std::size_t line = 1;
 
-        /// Error text.
-        const char *what() const noexcept;
+            /// Column.
+            std::size_t column = 1;
+        };
 
-        /// Error line in the source text.
-        std::size_t line() const noexcept;
+        /**
+         * A compilation error consists of an error message and position.
+         */
+        struct error
+        {
+        private:
+            char const *message;
+            source::position position;
 
-        /// Error column in the source text.
-        std::size_t column() const noexcept;
-    };
+        public:
+            /**
+             * \param message Error text.
+             * \param position Error position in the source text.
+             */
+            error(char const *message, const source::position position) noexcept;
 
-    template<typename T>
-    using result = boost::outcome_v2::result<T, CompileError>;
+            /// Error text.
+            const char *what() const noexcept;
+
+            /// Error line in the source text.
+            std::size_t line() const noexcept;
+
+            /// Error column in the source text.
+            std::size_t column() const noexcept;
+        };
+
+        template<typename T>
+        struct result
+        {
+            using E = std::forward_list<source::error>;
+
+            template<typename... Args>
+            explicit result(Args&&... arguments)
+                : payload(std::forward<Args>(arguments)...)
+            {
+            }
+
+            explicit result(const char *message, const source::position position)
+                : payload(E{ source::error(message, position) })
+            {
+            }
+
+            bool has_errors() const noexcept
+            {
+                return std::holds_alternative<E>(payload);
+            }
+
+            bool is_success() const noexcept
+            {
+                return std::holds_alternative<T>(payload);
+            }
+
+            T& success()
+            {
+                return std::get<T>(payload);
+            }
+
+            E& errors()
+            {
+                return std::get<E>(payload);
+            }
+
+        private:
+            std::variant<T, E> payload;
+        };
+    }
 
     enum class Target
     {
@@ -64,8 +106,7 @@ namespace elna
     {
         Symbol(const char *name);
         const char *name;
-        unsigned char *text;
-        std::size_t length;
+        std::vector<std::byte> text;
         Reference symbols[3];
     };
 }
diff --git a/include/elna/riscv.hpp b/include/elna/riscv.hpp
index 3dba193..a55723d 100644
--- a/include/elna/riscv.hpp
+++ b/include/elna/riscv.hpp
@@ -87,6 +87,14 @@ namespace elna
         lbu = 0b100,
         lhu = 0b101,
         jalr = 0b000,
+        mul = 000,
+        mulh = 001,
+        mulhsu = 010,
+        mulhu = 011,
+        div = 100,
+        divu = 101,
+        rem = 110,
+        remu = 111
     };
 
     enum class Funct12 : std::uint8_t
@@ -98,7 +106,8 @@ namespace elna
     enum class Funct7 : std::uint8_t
     {
         none = 0,
-        sub = 0b0100000
+        sub = 0b0100000,
+        muldiv = 0b0000001
     };
 
     enum class BaseOpcode : std::uint8_t
@@ -124,7 +133,9 @@ namespace elna
         Instruction& s(std::uint32_t imm1, Funct3 funct3, XRegister rs1, XRegister rs2);
         Instruction& r(XRegister rd, Funct3 funct3, XRegister rs1, XRegister rs2, Funct7 funct7 = Funct7::none);
         Instruction& u(XRegister rd, std::uint32_t imm);
-        std::uint8_t *encode();
+
+        const std::byte *cbegin();
+        const std::byte *cend();
 
     private:
         std::uint32_t instruction{ 0 };
diff --git a/source/cl.cpp b/source/cl.cpp
index fa27377..b3090a8 100644
--- a/source/cl.cpp
+++ b/source/cl.cpp
@@ -24,7 +24,7 @@ namespace elna
         return result;
     }
 
-    int compile(const char *inFile, const char *outputFilename)
+    int compile(const std::filesystem::path& in_file, const std::filesystem::path& out_file)
     {
         ELFIO::elfio writer;
 
@@ -35,21 +35,23 @@ namespace elna
         writer.set_type(ELFIO::ET_REL);
         writer.set_machine(ELFIO::EM_RISCV);
 
-        auto sourceText = readSource(inFile);
+        auto sourceText = readSource(in_file.c_str());
         if (sourceText == nullptr)
         {
             return 3;
         }
-        CompileError *compileError = nullptr;
         size_t tokensCount{ 0 };
-        auto tokens = lex(sourceText, compileError, &tokensCount);
+        auto lex_result = lex::lex(sourceText);
         free(sourceText);
-        if (tokens == nullptr)
+        if (lex_result.has_errors())
         {
-            printf("%lu:%lu: %s\n", compileError->line(), compileError->column(), compileError->what());
+            for (const auto& compile_error : lex_result.errors())
+            {
+                printf("%lu:%lu: %s\n", compile_error.line(), compile_error.column(), compile_error.what());
+            }
             return 1;
         }
-        auto ast = parse(tokens, tokensCount);
+        auto ast = parse(lex_result.success().data(), tokensCount);
         if (ast == nullptr)
         {
             return 2;
@@ -61,7 +63,7 @@ namespace elna
         text_sec->set_type(ELFIO::SHT_PROGBITS);
         text_sec->set_flags(ELFIO::SHF_ALLOC | ELFIO::SHF_EXECINSTR);
         text_sec->set_addr_align(0x1);
-        text_sec->set_data(reinterpret_cast<const char *>(program.text), program.length);
+        text_sec->set_data(reinterpret_cast<const char *>(program.text.data()), program.text.size());
 
         // Create string table section
         ELFIO::section* str_sec = writer.sections.add(".strtab");
@@ -91,7 +93,7 @@ namespace elna
         ELFIO::symbol_section_accessor syma(writer, sym_sec);
         auto label_sym = syma.add_symbol(stra, ".CL0", 0x00000000, strlen("%d\n") + 1,
                 ELFIO::STB_LOCAL, ELFIO::STT_NOTYPE, 0, ro_sec->get_index());
-        syma.add_symbol(stra, program.name, 0x00000000, program.length,
+        syma.add_symbol(stra, program.name, 0x00000000, program.text.size(),
                 ELFIO::STB_GLOBAL, ELFIO::STT_FUNC, 0, text_sec->get_index());
         auto printf_sym = syma.add_symbol(stra, "printf", 0x00000000, 0,
                 ELFIO::STB_GLOBAL, ELFIO::STT_NOTYPE, 0, ELFIO::SHN_UNDEF);
@@ -115,21 +117,8 @@ namespace elna
         rela.add_entry(program.symbols[2].offset, printf_sym, 18 /* ELFIO::R_RISCV_CALL */);
         rela.add_entry(program.symbols[2].offset, printf_sym, 51 /* ELFIO::R_RISCV_RELAX */);
 
-        // Another method to add the same relocation entry at one step is:
-        // rela.add_entry( stra, "msg",
-        //                 syma, 29, 0,
-        //                 ELF_ST_INFO( STB_GLOBAL, STT_OBJECT ), 0,
-        //                 text_sec->get_index(),
-        //                 place_to_adjust, (unsigned char)R_386_RELATIVE );
-
-        /* We don't use local symbols here. There is no need to rearrange them.
-        // But, for the completeness, we do this just prior 'save'
-        syma.arrange_local_symbols([&](ELFIO::Elf_Xword first, ELFIO::Elf_Xword second) {
-            rela.swap_symbols( first, second );
-        }); */
-
         // Create ELF object file
-        writer.save(outputFilename);
+        writer.save(out_file);
 
         return 0;
     }
diff --git a/source/elna/backend.d b/source/elna/backend.d
deleted file mode 100644
index 50a7cf1..0000000
--- a/source/elna/backend.d
+++ /dev/null
@@ -1,93 +0,0 @@
-module elna.backend;
-
-import core.stdc.stdio;
-import core.stdc.stdlib;
-import core.stdc.string;
-import elna.elf;
-import elna.extended;
-import elna.lexer;
-import elna.parser;
-import elna.result;
-import std.algorithm;
-import std.sumtype;
-import std.typecons;
-import tanya.os.error;
-import tanya.container.array;
-import tanya.container.string;
-import tanya.memory.allocator;
-
-extern(C++, "elna")
-Symbol writeNext(Block ast) @nogc;
-
-extern(C++, "elna")
-char* readSource(const(char)* source) @nogc;
-
-extern(C++, "elna")
-int compile(const(char)* inFile, const(char)* outputFilename) @nogc;
-
-int generate(const(char)* inFile, const(char)* outputFilename) @nogc
-{
-    auto sourceText = readSource(inFile);
-    if (sourceText is null)
-    {
-        return 3;
-    }
-    CompileError compileError = void;
-    size_t tokensCount;
-    auto tokens = lex(sourceText, &compileError, &tokensCount);
-    free(sourceText);
-    if (tokens is null)
-    {
-        printf("%lu:%lu: %s\n", compileError.line, compileError.column, compileError.what);
-        return 1;
-    }
-    auto ast = parse(tokens, tokensCount);
-    if (ast is null)
-    {
-        return 2;
-    }
-    auto handle = File.open(outputFilename, BitFlags!(File.Mode)(File.Mode.truncate));
-
-    if (!handle.valid)
-    {
-        return 1;
-    }
-    auto program = writeNext(ast);
-    auto elf = Elf!ELFCLASS32(move(handle));
-    auto readOnlyData = Array!ubyte(cast(const(ubyte)[]) "%d\n".ptr[0 .. 4]); // With \0.
-    auto text = Array!ubyte(program.text[0 .. program.length]);
-
-    elf.addReadOnlyData(String(".CL0"), readOnlyData);
-    elf.addCode(String(program.name[0 .. strlen(program.name)]), text);
-
-    elf.addExternSymbol(String("printf"));
-    foreach (ref reference; program.symbols)
-    {
-        elf.Rela relocationEntry = {
-            r_offset: cast(elf.Addr) reference.offset
-        };
-        elf.Rela relocationSub = {
-            r_offset: cast(elf.Addr) reference.offset,
-            r_info: R_RISCV_RELAX
-        };
-
-        final switch (reference.target)
-        {
-            case Target.text:
-                relocationEntry.r_info = R_RISCV_CALL;
-                break;
-            case Target.high20:
-                relocationEntry.r_info = R_RISCV_HI20;
-                break;
-            case Target.lower12i:
-                relocationEntry.r_info = R_RISCV_LO12_I;
-                break;
-        }
-
-        elf.relocate(String(reference.name[0 .. strlen(reference.name)]), relocationEntry, relocationSub);
-    }
-
-    elf.finish();
-
-    return 0;
-}
diff --git a/source/elna/elf.d b/source/elna/elf.d
deleted file mode 100644
index 81dd7da..0000000
--- a/source/elna/elf.d
+++ /dev/null
@@ -1,1060 +0,0 @@
-module elna.elf;
-
-import elna.extended;
-import elna.result;
-import std.algorithm;
-import tanya.container.array;
-import tanya.container.hashtable;
-import tanya.container.string;
-
-/// Unsigned program address.
-alias Elf64_Addr = ulong;
-/// Unsigned file offset.
-alias Elf64_Off = ulong;
-/// Unsigned medium integer.
-alias Elf64_Half = ushort;
-/// Unsigned integer.
-alias Elf64_Word = uint;
-/// Signed integer.
-alias Elf64_Sword = int;
-/// Unsigned long integer.
-alias Elf64_Xword = ulong;
-/// Signed long integer.
-alias Elf64_Sxword = long;
-
-/// Unsigned program address.
-alias Elf32_Addr = uint;
-/// Unsigned file offset.
-alias Elf32_Off = uint;
-/// Unsigned medium integer.
-alias Elf32_Half = ushort;
-/// Unsigned integer.
-alias Elf32_Word = uint;
-/// Signed integer.
-alias Elf32_Sword = int;
-
-enum : size_t
-{
-    /// File identification.
-    EI_MAG0 = 0,
-    /// File identification.
-    EI_MAG1 = 1,
-    /// File identification.
-    EI_MAG2 = 2,
-    /// File identification.
-    EI_MAG3 = 3,
-    /// File class.
-    EI_CLASS = 4,
-    /// Data encoding.
-    EI_DATA = 5,
-    /// File version.
-    EI_VERSION = 6,
-    /// Start of padding bytes.
-    EI_PAD = 7,
-    /// Size of e_ident[]
-    EI_NIDENT = 16
-}
-
-enum : ubyte
-{
-    /// e_ident[EI_MAG0].
-    ELFMAG0 = 0x7f,
-    /// e_ident[EI_MAG1].
-    ELFMAG1 = 'E',
-    /// e_ident[EI_MAG2].
-    ELFMAG2 = 'L',
-    /// e_ident[EI_MAG3].
-    ELFMAG3 = 'F'
-}
-
-/**
- * File header.
- */
-struct Elf64_Ehdr
-{
-    /// ELF identification.
-    ubyte[EI_NIDENT] e_ident;
-    /// Object file type.
-    Elf64_Half e_type;
-    /// Machine type.
-    Elf64_Half e_machine;
-    /// Object file version
-    Elf64_Word e_version;
-    /// Entry point address.
-    Elf64_Addr e_entry;
-    /// Program header offset.
-    Elf64_Off e_phoff;
-    /// Section header offset.
-    Elf64_Off e_shoff;
-    /// Processor-specific flags.
-    Elf64_Word e_flags;
-    /// ELF header size.
-    Elf64_Half e_ehsize;
-    /// Size of program header entry.
-    Elf64_Half e_phentsize;
-    /// Number of program header entries.
-    Elf64_Half e_phnum;
-    /// Size of section header entry.
-    Elf64_Half e_shentsize;
-    /// Number of section header entries.
-    Elf64_Half e_shnum;
-    /// Section name string table index.
-    Elf64_Half e_shstrndx;
-}
-
-/**
- * File header.
- */
-struct Elf32_Ehdr {
-    /// ELF identification.
-    ubyte[EI_NIDENT] e_ident;
-    /// Object file type.
-    Elf32_Half e_type;
-    /// Machine type.
-    Elf32_Half e_machine;
-    /// Object file version
-    Elf32_Word e_version;
-    /// Entry point address.
-    Elf32_Addr e_entry;
-    /// Program header offset.
-    Elf32_Off e_phoff;
-    /// Section header offset.
-    Elf32_Off e_shoff;
-    /// Processor-specific flags.
-    Elf32_Word e_flags;
-    /// ELF header size.
-    Elf32_Half e_ehsize;
-    /// Size of program header entry.
-    Elf32_Half e_phentsize;
-    /// Number of program header entries.
-    Elf32_Half e_phnum;
-    /// Size of section header entry.
-    Elf32_Half e_shentsize;
-    /// Number of section header entries.
-    Elf32_Half e_shnum;
-    /// Section name string table index.
-    Elf32_Half e_shstrndx;
-}
-
-/**
- * Section header.
- */
-struct Elf64_Shdr
-{
-    /// Section name.
-    Elf64_Word sh_name;
-    /// Section type.
-    Elf64_Word sh_type;
-    /// Section attributes.
-    Elf64_Xword sh_flags;
-    /// Virtual address in memory.
-    Elf64_Addr sh_addr;
-    /// Offset in file.
-    Elf64_Off sh_offset;
-    /// Size of section.
-    Elf64_Xword sh_size;
-    /// Link to other section.
-    Elf64_Word sh_link;
-    /// Miscellaneous information.
-    Elf64_Word sh_info;
-    /// Address alignment boundary.
-    Elf64_Xword sh_addralign;
-    /// Size of entries, if section has table.
-    Elf64_Xword sh_entsize;
-}
-
-/**
- * Section header.
- */
-struct Elf32_Shdr
-{
-    /// Section name.
-    Elf32_Word sh_name;
-    /// Section type.
-    Elf32_Word sh_type;
-    /// Section attributes.
-    Elf32_Word sh_flags;
-    /// Virtual address in memory.
-    Elf32_Addr sh_addr;
-    /// Offset in file.
-    Elf32_Off sh_offset;
-    /// Size of section.
-    Elf32_Word sh_size;
-    /// Link to other section.
-    Elf32_Word sh_link;
-    /// Miscellaneous information.
-    Elf32_Word sh_info;
-    /// Address alignment boundary.
-    Elf32_Word sh_addralign;
-    /// Size of entries, if section has table.
-    Elf32_Word sh_entsize;
-}
-
-/**
- * Symbol table entry.
- */
-struct Elf64_Sym
-{
-    /// Symbol name.
-    Elf64_Word st_name;
-    /// Type and Binding attributes.
-    ubyte st_info;
-    /// Reserved.
-    ubyte st_other;
-    /// Section table index.
-    Elf64_Half st_shndx;
-    /// Symbol value.
-    Elf64_Addr st_value;
-    /// Size of object (e.g., common).
-    Elf64_Xword st_size;
-}
-
-/**
- * Relocation entry.
- */
-struct Elf64_Rel
-{
-    /// Address of reference.
-    Elf64_Addr r_offset;
-    /// Symbol index and type of relocation.
-    Elf64_Xword r_info;
-}
-
-/**
- * Relocation entry with explicit addend.
- */
-struct Elf64_Rela
-{
-    /// Address of reference.
-    Elf64_Addr r_offset;
-    /// Symbol index and type of relocation.
-    Elf64_Xword r_info;
-    /// Constant part of expression.
-    Elf64_Sxword r_addend;
-}
-
-/**
- * Symbol table entry.
- */
-struct Elf32_Sym
-{
-    /// Symbol name.
-    Elf32_Word st_name;
-    /// Symbol value.
-    Elf32_Addr st_value;
-    /// Size of object (e.g., common).
-    Elf32_Word st_size;
-    /// Type and Binding attributes.
-    ubyte st_info;
-    /// Reserved.
-    ubyte st_other;
-    /// Section table index.
-    Elf32_Half st_shndx;
-}
-
-/**
- * Relocation entry.
- */
-struct Elf32_Rel
-{
-    /// Address of reference.
-    Elf32_Addr r_offset;
-    /// Symbol index and type of relocation.
-    Elf32_Word r_info;
-}
-
-/**
- * Relocation entry with explicit addend.
- */
-struct Elf32_Rela
-{
-    /// Address of reference.
-    Elf32_Addr r_offset;
-    /// Symbol index and type of relocation.
-    Elf32_Word r_info;
-    /// Constant part of expression.
-    Elf32_Sword r_addend;
-}
-
-/// Section Types, sh_type.
-enum : Elf64_Word
-{
-    /// Marks an unused section header.
-    SHT_NULL = 0,
-    ///  Contains information defined by the program.
-    SHT_PROGBITS = 1,
-    /// Contains a linker symbol table.
-    SHT_SYMTAB = 2,
-    /// Contains a string table.
-    SHT_STRTAB = 3,
-    /// Contains “Rela” type relocation entries.
-    SHT_RELA = 4,
-    /// Contains a symbol hash table
-    SHT_HASH = 5,
-    /// Contains dynamic linking tables
-    SHT_DYNAMIC = 6,
-    /// Contains note information
-    SHT_NOTE = 7,
-    /// Contains uninitialized space; does not occupy any space in the file.
-    SHT_NOBITS = 8,
-    /// Contains "Rel" type relocation entries.
-    SHT_REL = 9,
-    /// Reserved.
-    SHT_SHLIB = 10,
-    /// Contains a dynamic loader symbol table.
-    SHT_DYNSYM = 11,
-    /// Environment-specific use.
-    SHT_LOOS = 0x60000000,
-    SHT_HIOS = 0x6FFFFFFF,
-    /// Processor-specific use.
-    SHT_LOPROC = 0x70000000,
-    SHT_HIPROC = 0x7FFFFFFF,
-}
-
-/**
- * Section Attributes, sh_flags.
- */
-enum : Elf64_Xword
-{
-    /// Section contains writable data.
-    SHF_WRITE = 0x1,
-    /// Section is allocated in memory image of program.
-    SHF_ALLOC = 0x2,
-    /// Section contains executable instructions.
-    SHF_EXECINSTR = 0x4,
-    /// Environment-specific use.
-    SHF_MASKOS = 0x0F000000,
-    /// Processor-specific use.
-    SHF_MASKPROC = 0xF0000000,
-}
-
-ubyte ELF64_R_SYM(Elf64_Xword i) @nogc nothrow pure @safe
-{
-    return cast(ubyte) (i >> 32);
-}
-
-Elf64_Xword ELF64_R_TYPE(Elf64_Xword i) @nogc nothrow pure @safe
-{
-    return i & 0xffffffffL;
-}
-
-Elf64_Xword ELF64_R_INFO(Elf64_Xword s, Elf64_Xword t) @nogc nothrow pure @safe
-{
-    return (s << 32) + (t & 0xffffffffL);
-}
-
-ubyte ELF32_ST_BIND(ubyte i) @nogc nothrow pure @safe
-{
-    return i >> 4;
-}
-
-ubyte ELF32_ST_TYPE(ubyte i) @nogc nothrow pure @safe
-{
-    return i & 0xf;
-}
-
-ubyte ELF32_ST_INFO(Elf32_Word b, ubyte t) @nogc nothrow pure @safe
-{
-    return cast(ubyte) ((b << 4) + (t & 0xf));
-}
-
-Elf32_Word ELF32_R_SYM(Elf32_Word i) @nogc nothrow pure @safe
-{
-    return i >> 8;
-}
-
-ubyte ELF32_R_TYPE(Elf32_Word i) @nogc nothrow pure @safe
-{
-    return cast(ubyte) i;
-}
-
-Elf32_Word ELF32_R_INFO(Elf32_Word s, Elf32_Word t) @nogc nothrow pure @safe
-{
-    return (s << 8) + t;
-}
-
-enum : uint
-{
-    /// Not visible outside the object file.
-    STB_LOCAL = 0,
-    /// Global symbol, visible to all object files.
-    STB_GLOBAL = 1,
-    /// Global scope, but with lower precedence than global symbols.
-    STB_WEAK = 2,
-    /// Environment-specific use.
-    STB_LOOS = 10,
-    STB_HIOS = 12,
-    /// Processor-specific use.
-    STB_LOPROC = 13,
-    STB_HIPROC = 15,
-}
-
-enum : uint
-{
-    /// No type specified (e.g., an absolute symbol).
-    STT_NOTYPE = 0,
-    /// Data object.
-    STT_OBJECT = 1,
-    /// Function entry point.
-    STT_FUNC = 2,
-    /// Symbol is associated with a section.
-    STT_SECTION = 3,
-    /// Source file associated with the object file.
-    STT_FILE = 4,
-    /// Environment-specific use.
-    STT_LOOS = 10,
-    STT_HIOS = 12,
-    /// Processor-specific use.
-    STT_LOPROC = 13,
-    STT_HIPROC = 15,
-}
-
-/// Special Section Indices.
-enum : ushort
-{
-    /// Used to mark an undefined or meaningless section reference.
-    SHN_UNDEF = 0,
-    /// This value specifies the lower bound of the range of reserved indexes.
-    SHN_LORESERVE = 0xff00,
-    /// Processor-specific use.
-    SHN_LOPROC = 0xFF00,
-    SHN_HIPROC = 0xFF1F,
-    /// Environment-specific use.
-    SHN_LOOS = 0xFF20,
-    SHN_HIOS = 0xFF3F,
-    /// Indicates that the corresponding reference is an absolute value.
-    SHN_ABS = 0xFFF1,
-    /**
-     * Indicates a symbol that has been declared as a common block (Fortran
-     * COMMON or C tentative declaration).
-     */
-    SHN_COMMON = 0xFFF2,
-}
-
-/**
- * Object File Classes, e_ident[EI_CLASS].
- */
-enum : ubyte
-{
-    /// Invalid class.
-    ELFCLASSNONE = 0,
-    /// 32-bit objects.
-    ELFCLASS32 = 1,
-    /// 64-bit objects.
-    ELFCLASS64 = 2
-}
-
-enum : ubyte {
-    /// Invalid version.
-    EV_NONE = 0,
-    /// Current version.
-    EV_CURRENT = 1
-}
-
-/**
- * Data Encodings, e_ident[EI_DATA].
- */
-enum : ubyte
-{
-    /// Object file data structures are little-endian.
-    ELFDATA2LSB = 1,
-    /// Object file data structures are big-endian.
-    ELFDATA2MSB = 2,
-}
-
-/**
- * Operating System and ABI Identifiers, e_ident[EI_OSABI].
- */
-enum EI_OSABI : ubyte
-{
-    /// System V ABI.
-    ELFOSABI_SYSV = 0,
-    /// HP-UX operating system.
-    ELFOSABI_HPUX = 1,
-    /// Standalone (embedded) application.
-    ELFOSABI_STANDALONE = 255,
-}
-
-enum : Elf64_Half
-{
-    ET_NONE = 0, /// No file type.
-    ET_REL = 1, /// Relocatable object file.
-    ET_EXEC = 2, /// Executable file.
-    ET_DYN = 3, /// Shared object file.
-    ET_CORE = 4, /// Core file.
-    ET_LOOS = 0xFE00, /// Environment-specific use.
-    ET_HIOS = 0xFEFF,
-    ET_LOPROC = 0xFF00, /// Processor-specific use.
-    ET_HIPROC = 0xFFFF,
-}
-
-enum : ubyte
-{
-    R_RISCV_NONE = 0,
-    /// 32-bit relocation.
-    R_RISCV_32 = 1,
-    /// 64-bit relocation.
-    R_RISCV_64 = 2,
-    /// Relocation against a local symbol in a shared object.
-    R_RISCV_RELATIVE = 3,
-    /// Must be in executable; not allowed in shared library.
-    R_RISCV_COPY = 4,
-    /// Indicates the symbol associated with a PLT entry.
-    R_RISCV_JUMP_SLOT = 5,
-    R_RISCV_TLS_DTPMOD32 = 6,
-    R_RISCV_TLS_DTPMOD64 = 7,
-    R_RISCV_TLS_DTPREL32 = 8,
-    R_RISCV_TLS_DTPREL64 = 9,
-    R_RISCV_TLS_TPREL32 = 10,
-    R_RISCV_TLS_TPREL64 = 11,
-    /// 12-bit PC-relative branch offset.
-    R_RISCV_BRANCH = 16,
-    /// 20-bit PC-relative jump offset.
-    R_RISCV_JAL = 17,
-    /// 32-bit PC-relative function call, macros `call`, `tail`.
-    R_RISCV_CALL = 18,
-    /// 32-bit PC-relative function call, macros `call`, `tail` (PIC).
-    R_RISCV_CALL_PLT = 19,
-    /// High 20 bits of 32-bit PC-relative GOT access, `%got_pcrel_hi(symbol)`.
-    R_RISCV_GOT_HI20 = 20,
-    /// High 20 bits of 32-bit PC-relative TLS IE GOT access, macro `la.tls.ie`.
-    R_RISCV_TLS_GOT_HI20 = 21,
-    /// High 20 bits of 32-bit PC-relative TLS GD GOT reference, macro `la.tls.gd`.
-    R_RISCV_TLS_GD_HI20 = 22,
-    /// High 20 bits of 32-bit PC-relative reference, `%pcrel_hi(symbol)`.
-    R_RISCV_PCREL_HI20 = 23,
-    /// Low 12 bits of a 32-bit PC-relative, `%pcrel_lo(address of %pcrel_hi)`, the addend must be 0.
-    R_RISCV_PCREL_LO12_I = 24,
-    /// Low 12 bits of a 32-bit PC-relative, `%pcrel_lo(address of %pcrel_hi)`, the addend must be 0.
-    R_RISCV_PCREL_LO12_S = 25,
-    /// High 20 bits of 32-bit absolute address, `%hi(symbol)`.
-    R_RISCV_HI20 = 26,
-    /// Low 12 bits of 32-bit absolute address, `%lo(symbol)`.
-    R_RISCV_LO12_I = 27,
-    /// Low 12 bits of 32-bit absolute address, `%lo(symbol)`.
-    R_RISCV_LO12_S = 28,
-    /// High 20 bits of TLS LE thread pointer offset, `%tprel_hi(symbol)`.
-    R_RISCV_TPREL_HI20 = 29,
-    /// Low 12 bits of TLS LE thread pointer offset, `%tprel_lo(symbol)`.
-    R_RISCV_TPREL_LO12_I = 30,
-    /// Low 12 bits of TLS LE thread pointer offset, `%tprel_lo(symbol)`.
-    R_RISCV_TPREL_LO12_S = 31,
-    /// TLS LE thread pointer usage, `%tprel_add(symbol)`.
-    R_RISCV_TPREL_ADD = 32,
-    /// 8-bit label addition.
-    R_RISCV_ADD8 = 33,
-    /// 16-bit label addition.
-    R_RISCV_ADD16 = 34,
-    /// 32-bit label addition.
-    R_RISCV_ADD32 = 35,
-    /// 64-bit label addition.
-    R_RISCV_ADD64 = 36,
-    /// 8-bit label subtraction.
-    R_RISCV_SUB8 = 37,
-    /// 16-bit label subtraction.
-    R_RISCV_SUB16 = 38,
-    /// 32-bit label subtraction.
-    R_RISCV_SUB32 = 39,
-    /// 64-bit label subtraction.
-    R_RISCV_SUB64 = 40,
-    /// GNU {Cpp} vtable hierarchy.
-    R_RISCV_GNU_VTINHERIT = 41,
-    /// GNU {Cpp} vtable member usage.
-    R_RISCV_GNU_VTENTRY = 42,
-    /// Alignment statement.
-    R_RISCV_ALIGN = 43,
-    /// 8-bit PC-relative branch offset.
-    R_RISCV_RVC_BRANCH = 44,
-    /// 11-bit PC-relative jump offset.
-    R_RISCV_RVC_JUMP = 45,
-    /// High 6 bits of 18-bit absolute address.
-    R_RISCV_RVC_LUI = 46,
-    /// Instruction can be relaxed, paired with a normal relocation at the same address.
-    R_RISCV_RELAX = 51,
-    /// Local label subtraction.
-    R_RISCV_SUB6 = 52,
-    /// Local label assignment.
-    R_RISCV_SET6 = 53,
-    /// Local label assignment.
-    R_RISCV_SET8 = 54,
-    /// Local label assignment.
-    R_RISCV_SET16 = 55,
-    /// Local label assignment.
-    R_RISCV_SET32 = 56,
-    /// 32-bit PC relative.
-    R_RISCV_32_PCREL = 57,
-    /// Relocation against a local ifunc symbol in a shared object.
-    R_RISCV_IRELATIVE = 58
-}
-
-auto pad(ubyte elfClass)(size_t value) @nogc
-{
-    static if (elfClass == ELFCLASS32)
-    {
-        return cast(Elf32_Word) (value / 4 + 1) * 4;
-    }
-    else static if (elfClass == ELFCLASS64)
-    {
-        return cast(Elf64_Xword) (value / 8 + 1) * 8;
-    }
-    else
-    {
-        static assert(false, "Invalid ELF class");
-    }
-}
-
-private struct Relocation(Sym, Rel)
-{
-    Sym symbol;
-    Array!Rel relocations;
-}
-
-struct Elf(ubyte elfClass)
-{
-    static if (elfClass == ELFCLASS32)
-    {
-        alias Addr = Elf32_Addr;
-        alias Off = Elf32_Off;
-        alias Half = Elf32_Half;
-        alias Word = Elf32_Word;
-        alias Sword = Elf32_Sword;
-        alias Xword = Elf32_Word;
-        alias Sxword = Elf32_Sword;
-
-        alias Ehdr = Elf32_Ehdr;
-        alias Shdr = Elf32_Shdr;
-        alias Rel = Elf32_Rel;
-        alias Rela = Elf32_Rela;
-        alias Sym = Elf32_Sym;
-
-        alias R_SYM = ELF32_R_SYM;
-        alias R_TYPE = ELF32_R_TYPE;
-        alias R_INFO = ELF32_R_INFO;
-        alias ST_BIND = ELF32_ST_BIND;
-        alias ST_TYPE = ELF32_ST_TYPE;
-        alias ST_INFO = ELF32_ST_INFO;
-    }
-    else static if (elfClass == ELFCLASS64)
-    {
-        alias Addr = Elf64_Addr;
-        alias Off = Elf64_Off;
-        alias Half = Elf64_Half;
-        alias Word = Elf64_Word;
-        alias Sword = Elf64_Sword;
-        alias Xword = Elf64_Xword;
-        alias Sxword = Elf64_Sxword;
-
-        alias Ehdr = Elf64_Ehdr;
-        alias Shdr = Elf64_Shdr;
-        alias Rel = Elf64_Rel;
-        alias Rela = Elf64_Rela;
-        alias Sym = Elf64_Sym;
-
-        alias R_SYM = ELF64_R_SYM;
-        alias R_TYPE = ELF64_R_TYPE;
-        alias R_INFO = ELF64_R_INFO;
-        alias ST_BIND = ELF64_ST_BIND;
-        alias ST_TYPE = ELF64_ST_TYPE;
-        alias ST_INFO = ELF64_ST_INFO;
-    }
-    else
-    {
-        static assert(false, "Invalid ELF class");
-    }
-
-    private alias Relocation = .Relocation!(Sym, Rela);
-
-    private Array!Shdr sectionHeaders;
-    private Off currentOffset = Elf32_Ehdr.sizeof;
-    static immutable char[52] sections =
-        "\0.symtab\0.strtab\0.shstrtab\0.text\0.rodata\0.rela.text\0";
-    private String strings;
-    private File output;
-    private Array!ubyte readOnly;
-
-    private HashTable!(String, Relocation) symbolTable;
-
-    private enum HeaderName
-    {
-        text = 0x1b,
-        roData = 0x21,
-        string_ = 0x09,
-        headerString = 0x11,
-        symbol = 0x01,
-        rela = 0x29
-    }
-
-    static Elf opCall(File output) @nogc
-    {
-        Elf elf = Elf.init;
-
-        elf.initializeSectionHeaders();
-        elf.output = move(output);
-
-        elf.output.seek(Ehdr.sizeof, File.Whence.set);
-
-        elf.makeTextHeader();
-        elf.makeRoDataHeader();
-        elf.makeSymbolHeader();
-        elf.makeRelaHeader();
-        elf.makeStringHeader!(HeaderName.string_)();
-        elf.makeStringHeader!(HeaderName.headerString)();
-
-        return elf;
-    }
-
-    @disable this(this);
-
-    void finish() @nogc
-    {
-        writeRoDataTable();
-        writeSymbolTable();
-        writeStringTables();
-
-        // End writing data, start writing headers.
-
-        output.write((cast(ubyte*) this.sectionHeaders.get)[0 .. Shdr.sizeof * this.sectionHeaders.length]);
-
-        writeFileHeader();
-    }
-
-    private Sym initializeSymbols() @nogc
-    {
-        // Zero symbol
-        Sym symbol;
-        symbol.st_name = 0; // Word
-        symbol.st_value = 0; // Addr
-        symbol.st_size = 0; // Word
-        symbol.st_info = 0; // char
-        symbol.st_other = 0; // char
-        symbol.st_shndx = 0; // Half word
-
-        return symbol;
-    }
-
-    private void makeStringHeader(HeaderName position)() @nogc
-    {
-        Shdr table;
-
-        table.sh_name = position;
-        table.sh_type = SHT_STRTAB;
-        table.sh_flags = 0;
-        table.sh_addr = 0;
-        table.sh_offset = 0;
-        table.sh_size = 0;
-        table.sh_link = SHN_UNDEF;
-        table.sh_info = 0;
-        table.sh_addralign = 1;
-        table.sh_entsize = 0;
-
-        this.sectionHeaders.insertBack(table);
-    }
-
-    private void writeStringTables() @nogc
-    {
-        auto stringIndex = findHeader!(HeaderName.string_);
-        assert(stringIndex != -1);
-
-        this.sectionHeaders[stringIndex].sh_offset = this.currentOffset;
-        this.sectionHeaders[stringIndex].sh_size = cast(Word) strings.length;
-
-        output.write(cast(ubyte[]) this.strings.toStringz[0 .. this.strings.length + 1]);
-        this.currentOffset += this.strings.length + 1;
-
-        auto headerStringIndex = findHeader!(HeaderName.headerString);
-        assert(stringIndex != -1);
-
-        this.sectionHeaders[headerStringIndex].sh_offset = this.currentOffset;
-        this.sectionHeaders[headerStringIndex].sh_size = cast(Word) sections.length;
-
-        output.write(cast(const(ubyte)[]) this.sections);
-        this.currentOffset += this.sections.length;
-        auto alignment = pad!ELFCLASS32(this.strings.length + 1 + this.sections.length);
-        const(ubyte)[4] padding = 0;
-        output.write(padding[0 .. alignment - this.strings.length - 1 - this.sections.length]);
-        this.currentOffset += alignment - this.strings.length - 1 - this.sections.length;
-    }
-
-    private void makeSymbolHeader() @nogc
-    {
-        Shdr symbolTableHeader;
-
-        symbolTableHeader.sh_name = HeaderName.symbol;
-        symbolTableHeader.sh_type = SHT_SYMTAB;
-        symbolTableHeader.sh_flags = 0;
-        symbolTableHeader.sh_addr = 0;
-        symbolTableHeader.sh_offset = 0;
-        symbolTableHeader.sh_size = 0;
-        // String table used by entries in this section.
-        symbolTableHeader.sh_link = 0;
-        symbolTableHeader.sh_info = 0;
-        symbolTableHeader.sh_addralign = 4;
-        symbolTableHeader.sh_entsize = Sym.sizeof;
-
-        this.sectionHeaders.insertBack(symbolTableHeader);
-    }
-
-    private void writeSymbolTable() @nogc
-    {
-        const index = findHeader!(HeaderName.symbol)();
-        const stringIndex = findHeader!(HeaderName.string_)();
-        const relaIndex = findHeader!(HeaderName.rela);
-        const textIndex = findHeader!(HeaderName.text)();
-
-        assert(index != -1);
-        assert(stringIndex != -1);
-        assert(relaIndex != -1);
-        assert(textIndex != -1);
-
-        this.sectionHeaders[index].sh_offset = this.currentOffset;
-        this.sectionHeaders[index].sh_link = cast(Word) stringIndex;
-        this.sectionHeaders[index].sh_size = cast(Word) ((1 + symbolTable.length) * Sym.sizeof);
-
-        this.sectionHeaders[relaIndex].sh_link = cast(Word) index;
-        this.sectionHeaders[relaIndex].sh_info = cast(Word) textIndex;
-        this.sectionHeaders[relaIndex].sh_offset = this.sectionHeaders[index].sh_offset
-            + this.sectionHeaders[index].sh_size;
-
-        auto initialSymbol = initializeSymbols();
-        output.write((cast(ubyte*) &initialSymbol)[0 .. Sym.sizeof]);
-        this.currentOffset += Sym.sizeof;
-
-        int i = 1;
-        Array!Relocation symbols = Array!Relocation(this.symbolTable.byValue());
-        auto rightRange = symbols[].partition!(symbol => ST_BIND(symbol.symbol.st_info) != STB_GLOBAL);
-
-        // Greater than last local symbol.
-        this.sectionHeaders[index].sh_info = cast(Word) (symbols.length - rightRange.length + 1);
-
-        foreach (ref symbol; symbols[])
-        {
-            this.output.seek(this.sectionHeaders[relaIndex].sh_offset + this.sectionHeaders[relaIndex].sh_size,
-                    File.Whence.set);
-
-            if (!symbol.relocations.empty)
-            {
-                foreach (ref relocation; symbol.relocations[])
-                {
-                    relocation.r_info = R_INFO(i, R_TYPE(relocation.r_info));
-                }
-                this.sectionHeaders[relaIndex].sh_flags = SHF_ALLOC;
-                const size = cast(Word) (Rela.sizeof * symbol.relocations.length);
-
-                this.output.write((cast(ubyte*) symbol.relocations.get)[0 .. size]);
-                this.sectionHeaders[relaIndex].sh_size += size;
-                this.currentOffset += size;
-            }
-
-            this.output.seek(this.sectionHeaders[index].sh_offset + i * Sym.sizeof, File.Whence.set);
-            output.write((cast(ubyte*) &symbol)[0 .. Sym.sizeof]);
-            this.currentOffset += Sym.sizeof;
-            ++i;
-        }
-        this.output.seek(0, File.Whence.end);
-    }
-
-    void addCode(String name, ref Array!ubyte text)
-    @nogc
-    {
-        this.output.write(text.get);
-
-        auto textHeaderIndex = findHeader!(HeaderName.text)();
-        assert(textHeaderIndex != -1);
-
-        this.strings.insertBack("\0");
-
-        Sym symbol;
-        // Main function
-        symbol.st_name = cast(Word) this.strings.length;
-        symbol.st_value = 0;
-        symbol.st_size = cast(Word) text.length;
-        symbol.st_info = ST_INFO(STB_GLOBAL, STT_FUNC);
-        symbol.st_other = 0; // char
-         // .text header index, half word
-        symbol.st_shndx = cast(Half) textHeaderIndex;
-        this.symbolTable[name] = Relocation(symbol);
-
-        this.strings.insertBack(name[]);
-
-        this.sectionHeaders[textHeaderIndex].sh_size += text.length;
-        this.currentOffset += text.length;
-    }
-
-    void addReadOnlyData(String name, ref Array!ubyte data) @nogc
-    {
-        auto roDataIndex = findHeader!(HeaderName.roData)();
-        assert(roDataIndex != -1);
-
-        this.strings.insertBack("\0");
-
-        Sym symbol;
-        // Main function
-        symbol.st_name = cast(Word) this.strings.length;
-        symbol.st_value = 0;
-        symbol.st_size = cast(Word) data.length;
-        symbol.st_info = ST_INFO(STB_LOCAL, STT_NOTYPE);
-        symbol.st_other = 0; // char
-         // .text header index, half word
-        symbol.st_shndx = cast(Half) roDataIndex;
-        this.symbolTable[name] = Relocation(symbol);
-
-        this.strings.insertBack(name[]);
-        this.readOnly.insertBack(data[]);
-    }
-
-    void addExternSymbol(String name) @nogc
-    {
-        Sym usedSymbolEntry;
-
-        this.strings.insertBack("\0");
-        usedSymbolEntry.st_name = cast(Word) this.strings.length;
-        usedSymbolEntry.st_value = 0;
-        usedSymbolEntry.st_size = 0;
-        usedSymbolEntry.st_info = ST_INFO(STB_GLOBAL, STT_NOTYPE);
-        usedSymbolEntry.st_other = 0;
-        usedSymbolEntry.st_shndx = SHN_UNDEF;
-
-        this.strings.insertBack(name[]);
-        this.strings.insertBack("\0");
-        this.symbolTable[name] = Relocation(usedSymbolEntry);
-    }
-
-    void relocate(String name, Rela[] usedSymbols...) @nogc
-    {
-        foreach (usedSymbol; usedSymbols)
-        {
-            Rela relocationEntry = usedSymbol;
-
-            relocationEntry.r_info = usedSymbol.r_info;
-            this.symbolTable[name].relocations.insertBack(relocationEntry);
-        }
-    }
-
-    private ptrdiff_t findHeader(HeaderName position)()
-    {
-        return countUntil!(header => header.sh_name == position)(this.sectionHeaders[]);
-    }
-
-    private void makeTextHeader() @nogc
-    {
-        Shdr textHeader;
-
-        textHeader.sh_name = HeaderName.text;
-        textHeader.sh_type = SHT_PROGBITS;
-        textHeader.sh_flags = SHF_EXECINSTR | SHF_ALLOC;
-        textHeader.sh_addr = 0;
-        textHeader.sh_offset = this.currentOffset;
-        textHeader.sh_size = 0;
-        textHeader.sh_link = SHN_UNDEF;
-        textHeader.sh_info = 0;
-        textHeader.sh_addralign = 1;
-        textHeader.sh_entsize = 0;
-
-        this.sectionHeaders.insertBack(textHeader);
-    }
-
-    private void initializeSectionHeaders() @nogc
-    {
-        Shdr table;
-
-        table.sh_name = 0;
-        table.sh_type = SHT_NULL;
-        table.sh_flags = 0;
-        table.sh_addr = 0;
-        table.sh_offset = 0;
-        table.sh_size = 0;
-        table.sh_link = SHN_UNDEF;
-        table.sh_info = 0;
-        table.sh_addralign = 0;
-        table.sh_entsize = 0;
-
-        this.sectionHeaders.insertBack(table);
-    }
-
-    private void writeFileHeader() @nogc
-    {
-        Ehdr fileHeader;
-        auto headerStringIndex = findHeader!(HeaderName.headerString)();
-
-        assert(headerStringIndex != -1);
-
-        // Magic number.
-        fileHeader.e_ident[0] = '\x7f';
-        fileHeader.e_ident[1] = 'E';
-        fileHeader.e_ident[2] = 'L';
-        fileHeader.e_ident[3] = 'F';
-
-        fileHeader.e_ident[4] = ELFCLASS32;
-        fileHeader.e_ident[5] = ELFDATA2LSB;
-        fileHeader.e_ident[6] = EV_CURRENT;
-        fileHeader.e_ident[7] = EI_OSABI.ELFOSABI_SYSV;
-        fileHeader.e_ident[8] = 0;
-
-        fileHeader.e_type = ET_REL;
-        fileHeader.e_machine = 0xf3; // EM_RISCV
-        fileHeader.e_version = EV_CURRENT;
-        fileHeader.e_entry = 0;
-        fileHeader.e_phoff = 0;
-        fileHeader.e_shoff = this.currentOffset;
-        fileHeader.e_flags = 0;
-        fileHeader.e_ehsize = Elf32_Ehdr.sizeof;
-        fileHeader.e_phentsize = 0;
-        fileHeader.e_phnum = 0;
-        fileHeader.e_shentsize = Elf32_Shdr.sizeof;
-        fileHeader.e_shnum = cast(Elf32_Half) this.sectionHeaders.length;
-
-        // String table is the last one
-        fileHeader.e_shstrndx = cast(Half) headerStringIndex;
-
-        output.seek(0, File.Whence.set);
-        output.write((cast(ubyte*) &fileHeader)[0 .. fileHeader.sizeof]);
-    }
-
-    private void makeRoDataHeader() @nogc
-    {
-        Shdr table;
-
-        table.sh_name = HeaderName.roData;
-        table.sh_type = SHT_PROGBITS;
-        table.sh_flags = SHF_ALLOC;
-        table.sh_addr = 0;
-        table.sh_offset = 0;
-        table.sh_size = 0;
-        table.sh_link = SHN_UNDEF;
-        table.sh_info = 0;
-        table.sh_addralign = 4;
-        table.sh_entsize = 0;
-
-        this.sectionHeaders.insertBack(table);
-    }
-
-    private void writeRoDataTable() @nogc
-    {
-        auto index = findHeader!(HeaderName.roData)();
-        assert(index != -1);
-
-        this.sectionHeaders[index].sh_offset = this.currentOffset;
-        this.sectionHeaders[index].sh_size = cast(Xword) this.readOnly.length;
-
-        output.write(this.readOnly.get);
-        this.currentOffset += this.readOnly.length;
-    }
-
-    private void makeRelaHeader() @nogc
-    {
-        Shdr table;
-
-        table.sh_name = HeaderName.rela;
-        table.sh_type = SHT_RELA;
-        table.sh_flags = 0;
-        table.sh_addr = 0;
-        table.sh_offset = 0;
-        table.sh_size = 0;
-        table.sh_link = SHN_UNDEF;
-        table.sh_info = 0;
-        table.sh_addralign = 4;
-        table.sh_entsize = Rela.sizeof;
-
-        this.sectionHeaders.insertBack(table);
-    }
-}
diff --git a/source/elna/extended.d b/source/elna/extended.d
deleted file mode 100644
index 6baea71..0000000
--- a/source/elna/extended.d
+++ /dev/null
@@ -1,335 +0,0 @@
-/**
- * File I/O that can be moved into more generic library when and if finished.
- */
-module elna.extended;
-
-import core.stdc.errno;
-import core.stdc.stdio;
-import std.sumtype;
-import std.typecons;
-import tanya.os.error;
-import tanya.container.array;
-import tanya.container.string;
-
-/**
- * File handle abstraction.
- */
-struct File
-{
-    /// Plattform dependent file type.
-    alias Handle = FILE*;
-
-    /// Uninitialized file handle value.
-    enum Handle invalid = null;
-
-    /**
-     * Relative position.
-     */
-    enum Whence
-    {
-        /// Relative to the start of the file.
-        set = SEEK_SET,
-        /// Relative to the current cursor position.
-        currentt = SEEK_CUR,
-        /// Relative from the end of the file.
-        end = SEEK_END,
-    }
-
-    /**
-     * File open modes.
-     */
-    enum Mode
-    {
-        /// Open the file for reading.
-        read = 1 << 0,
-        /// Open the file for writing. The stream is positioned at the beginning
-        /// of the file.
-        write = 1 << 1,
-        /// Open the file for writing and remove its contents.
-        truncate = 1 << 2,
-        /// Open the file for writing. The stream is positioned at the end of
-        /// the file.
-        append = 1 << 3,
-    }
-
-    private enum Status
-    {
-        invalid,
-        owned,
-        borrowed,
-    }
-
-    private union Storage
-    {
-        Handle handle;
-        ErrorCode errorCode;
-    }
-    private Storage storage;
-    private Status status = Status.invalid;
-
-    @disable this(scope return ref File f);
-    @disable this();
-
-    /**
-     * Closes the file.
-     */
-    ~this() @nogc nothrow
-    {
-        if (this.status == Status.owned)
-        {
-            fclose(this.storage.handle);
-        }
-        this.storage.handle = invalid;
-        this.status = Status.invalid;
-    }
-
-    /**
-     * Construct the object with the given system handle. The won't be claused
-     * in the descructor if this constructor is used.
-     *
-     * Params:
-     *   handle = File handle to be wrapped by this structure.
-     */
-    this(Handle handle) @nogc nothrow pure @safe
-    {
-        this.storage.handle = handle;
-        this.status = Status.borrowed;
-    }
-
-    /**
-     * Returns: Plattform dependent file handle.
-     */
-    @property Handle handle() @nogc nothrow pure @trusted
-    {
-        return valid ? this.storage.handle : invalid;
-    }
-
-    /**
-     * Returns: An error code if an error has occurred.
-     */
-    @property ErrorCode errorCode() @nogc nothrow pure @safe
-    {
-        return valid ? ErrorCode() : this.storage.errorCode;
-    }
-
-    /**
-     * Returns: Whether a valid, opened file is represented.
-     */
-    @property bool valid() @nogc nothrow pure @safe
-    {
-        return this.status != Status.invalid;
-    }
-
-    /**
-     * Transfers the file into invalid state.
-     *
-     * Returns: The old file handle.
-     */
-    Handle reset() @nogc nothrow pure @safe
-    {
-        if (!valid)
-        {
-            return invalid;
-        }
-        auto oldHandle = handle;
-
-        this.status = Status.invalid;
-        this.storage.errorCode = ErrorCode();
-
-        return oldHandle;
-    }
-
-    /**
-     * Sets stream position in the file.
-     *
-     * Params:
-     *   offset = File offset.
-     *   whence = File position to add the offset to.
-     *
-     * Returns: Error code if any.
-     */
-    ErrorCode seek(size_t offset, Whence whence) @nogc nothrow
-    {
-        if (!valid)
-        {
-            return ErrorCode(ErrorCode.ErrorNo.badDescriptor);
-        }
-        if (fseek(this.storage.handle, offset, whence))
-        {
-            return ErrorCode(cast(ErrorCode.ErrorNo) errno);
-        }
-        return ErrorCode();
-    }
-
-    /**
-     * Returns: Current offset or an error.
-     */
-    SumType!(ErrorCode, size_t) tell() @nogc nothrow
-    {
-        if (!valid)
-        {
-            return typeof(return)(ErrorCode(ErrorCode.ErrorNo.badDescriptor));
-        }
-        auto result = ftell(this.storage.handle);
-
-        if (result < 0)
-        {
-            return typeof(return)(ErrorCode(cast(ErrorCode.ErrorNo) errno));
-        }
-        return typeof(return)(cast(size_t) result);
-    }
-
-    /**
-     * Params:
-     *   buffer = Destination buffer.
-     *
-     * Returns: Bytes read. $(D_PSYMBOL ErrorCode.ErrorNo.success) means that
-     *          while reading the file an unknown error has occurred.
-     */
-    SumType!(ErrorCode, size_t) read(ubyte[] buffer) @nogc nothrow
-    {
-        if (!valid)
-        {
-            return typeof(return)(ErrorCode(ErrorCode.ErrorNo.badDescriptor));
-        }
-        const bytesRead = fread(buffer.ptr, 1, buffer.length, this.storage.handle);
-        if (bytesRead == buffer.length || eof())
-        {
-            return typeof(return)(bytesRead);
-        }
-        return typeof(return)(ErrorCode());
-    }
-
-    /**
-     * Params:
-     *   buffer = Source buffer.
-     *
-     * Returns: Bytes written. $(D_PSYMBOL ErrorCode.ErrorNo.success) means that
-     *          while reading the file an unknown error has occurred.
-     */
-    SumType!(ErrorCode, size_t) write(const(ubyte)[] buffer) @nogc nothrow
-    {
-        if (!valid)
-        {
-            return typeof(return)(ErrorCode(ErrorCode.ErrorNo.badDescriptor));
-        }
-        const bytesWritten = fwrite(buffer.ptr, 1, buffer.length, this.storage.handle);
-        if (bytesWritten == buffer.length)
-        {
-            return typeof(return)(buffer.length);
-        }
-        return typeof(return)(ErrorCode());
-    }
-
-    /**
-     * Returns: EOF status of the file.
-     */
-    bool eof() @nogc nothrow
-    {
-        return valid && feof(this.storage.handle) != 0;
-    }
-
-    /**
-     * Constructs a file object that will be closed in the destructor.
-     *
-     * Params:
-     *   filename = The file to open.
-     *
-     * Returns: Opened file or an error.
-     */
-    static File open(const(char)* filename, BitFlags!Mode mode) @nogc nothrow
-    {
-        char[3] modeBuffer = "\0\0\0";
-
-        if (mode.truncate)
-        {
-            modeBuffer[0] = 'w';
-            if (mode.read)
-            {
-                modeBuffer[1] = '+';
-            }
-        }
-        else if (mode.append)
-        {
-            modeBuffer[0] = 'a';
-            if (mode.read)
-            {
-                modeBuffer[1] = '+';
-            }
-        }
-        else if (mode.read)
-        {
-            modeBuffer[0] = 'r';
-            if (mode.write)
-            {
-                modeBuffer[1] = '+';
-            }
-        }
-
-        auto newHandle = fopen(filename, modeBuffer.ptr);
-        auto newFile = File(newHandle);
-
-        if (newHandle is null)
-        {
-            newFile.status = Status.invalid;
-            newFile.storage.errorCode = ErrorCode(cast(ErrorCode.ErrorNo) errno);
-        }
-        else
-        {
-            if (mode == BitFlags!Mode(Mode.write))
-            {
-                rewind(newHandle);
-            }
-            newFile.status = Status.owned;
-        }
-
-        return newFile;
-    }
-}
-
-/**
- * Reads the whole file and returns its contents.
- *
- * Params:
- *   sourceFilename = Source filename.
- *
- * Returns: File contents or an error.
- *
- * See_Also: $(D_PSYMBOL File.read)
- */
-SumType!(ErrorCode, Array!ubyte) readFile(const(char)* sourceFilename) @nogc
-{
-    enum size_t bufferSize = 255;
-    auto sourceFile = File.open(sourceFilename, BitFlags!(File.Mode)(File.Mode.read));
-
-    if (!sourceFile.valid)
-    {
-        return typeof(return)(sourceFile.errorCode);
-    }
-    Array!ubyte sourceText;
-    size_t totalRead;
-    size_t bytesRead;
-    do
-    {
-        sourceText.length = sourceText.length + bufferSize;
-        const readStatus = sourceFile
-            .read(sourceText[totalRead .. $].get)
-            .match!(
-                (ErrorCode errorCode) => nullable(errorCode),
-                (size_t bytesRead_) {
-                    bytesRead = bytesRead_;
-                    return Nullable!ErrorCode();
-                }
-            );
-        if (!readStatus.isNull)
-        {
-            return typeof(return)(readStatus.get);
-        }
-        totalRead += bytesRead;
-    }
-    while (bytesRead == bufferSize);
-
-    sourceText.length = totalRead;
-
-    return typeof(return)(sourceText);
-}
diff --git a/source/elna/lexer.d b/source/elna/lexer.d
deleted file mode 100644
index eb0d6dd..0000000
--- a/source/elna/lexer.d
+++ /dev/null
@@ -1,55 +0,0 @@
-module elna.lexer;
-
-import core.stdc.string;
-import elna.result;
-
-extern(C++, "elna")
-struct Token
-{
-    enum Type : ushort
-    {
-        number = 0,
-        operator = 1,
-        let = 2,
-        identifier = 3,
-        equals = 4,
-        var = 5,
-        semicolon = 6,
-        leftParen = 7,
-        rightParen = 8,
-        bang = 9,
-        dot = 10,
-        comma = 11,
-    }
-
-    union Value
-    {
-        int number;
-        const(char)* identifier;
-    }
-
-    private Type type;
-    private Value value_;
-    private Position position_;
-
-    @disable this();
-
-    this(Type type, Position position) @nogc nothrow pure @safe;
-    this(Type type, int value, Position position) @nogc nothrow pure @trusted;
-    this(Type type, const(char)* value, Position position) @nogc nothrow;
-
-    /**
-     * Returns: Expected token type.
-     */
-    Type of() const @nogc nothrow pure @safe;
-    const(char)* identifier() const @nogc nothrow pure;
-    int number() const @nogc nothrow pure;
-
-    /**
-     * Returns: The token position in the source text.
-     */
-    @property const(Position) position() const @nogc nothrow pure @safe;
-}
-
-extern(C++, "elna")
-Token* lex(const(char)* buffer, CompileError* compileError, size_t* length) @nogc;
diff --git a/source/elna/parser.d b/source/elna/parser.d
deleted file mode 100644
index ca8064e..0000000
--- a/source/elna/parser.d
+++ /dev/null
@@ -1,110 +0,0 @@
-module elna.parser;
-
-import core.stdc.string;
-import core.stdc.stdlib;
-import elna.lexer;
-import elna.result;
-import tanya.memory.allocator;
-import std.array;
-
-/**
- * Parser visitor.
- */
-extern(C++, "elna")
-abstract class ParserVisitor
-{
-    abstract void visit(Node) @nogc;
-    abstract void visit(Definition) @nogc;
-    abstract void visit(BangStatement) @nogc;
-    abstract void visit(Block) @nogc;
-    abstract void visit(Expression) @nogc;
-    abstract void visit(BinaryExpression) @nogc;
-    abstract void visit(Variable) @nogc;
-    abstract void visit(Number) @nogc;
-}
-
-/**
- * AST node.
- */
-extern(C++, "elna")
-abstract class Node
-{
-    abstract void accept(ParserVisitor visitor) @nogc;
-}
-
-extern(C++, "elna")
-abstract class Statement : Node
-{
-}
-
-/**
- * Constant definition.
- */
-extern(C++, "elna")
-class Definition : Node
-{
-    Number number;
-    const(char)* identifier;
-
-    override void accept(ParserVisitor visitor) @nogc;
-}
-
-extern(C++, "elna")
-class BangStatement : Statement
-{
-    Expression expression;
-
-    override void accept(ParserVisitor visitor) @nogc;
-}
-
-extern(C++, "elna")
-class Block : Node
-{
-    Definition* definitions;
-    size_t definitionsLength;
-    Statement statement;
-
-    override void accept(ParserVisitor visitor) @nogc;
-}
-
-extern(C++, "elna")
-abstract class Expression : Node
-{
-    override void accept(ParserVisitor visitor) @nogc;
-}
-
-extern(C++, "elna")
-class Number : Expression
-{
-    int value;
-
-    override void accept(ParserVisitor visitor) @nogc;
-}
-
-extern(C++, "elna")
-class Variable : Expression
-{
-    const(char)* identifier;
-
-    override void accept(ParserVisitor visitor) @nogc;
-}
-
-extern(C++, "elna")
-enum BinaryOperator
-{
-    sum,
-    subtraction
-}
-
-extern(C++, "elna")
-class BinaryExpression : Expression
-{
-    Expression lhs, rhs;
-    BinaryOperator operator;
-
-    this(Expression lhs, Expression rhs, ubyte operator) @nogc;
-    override void accept(ParserVisitor visitor) @nogc;
-}
-
-extern(C++, "elna")
-Block parse(Token* tokenStream, size_t length) @nogc;
diff --git a/source/elna/result.d b/source/elna/result.d
deleted file mode 100644
index 2b0a521..0000000
--- a/source/elna/result.d
+++ /dev/null
@@ -1,101 +0,0 @@
-module elna.result;
-
-import std.typecons;
-import tanya.container.array;
-import tanya.container.string;
-
-/**
- * Position in the source text.
- */
-extern(C++, "elna")
-struct Position
-{
-    /// Line.
-    size_t line = 1;
-
-    /// Column.
-    size_t column = 1;
-}
-
-extern(C++, "elna")
-struct CompileError
-{
-    private const(char)* message_;
-
-    private Position position_;
-
-    @disable this();
-
-    /**
-     * Params:
-     *   message = Error text.
-     *   position = Error position in the source text.
-     */
-    this(const(char)* message, const Position position) @nogc nothrow pure @safe;
-
-    /// Error text.
-    @property const(char)* what() const @nogc nothrow pure @safe;
-
-    /// Error line in the source text.
-    @property size_t line() const @nogc nothrow pure @safe;
-
-    /// Error column in the source text.
-    @property size_t column() const @nogc nothrow pure @safe;
-}
-
-struct Result(T)
-{
-    Nullable!CompileError error;
-    T result;
-
-    this(T result)
-    {
-        this.result = result;
-        this.error = typeof(this.error).init;
-    }
-
-    this(const(char)* message, Position position)
-    {
-        this.result = T.init;
-        this.error = CompileError(message, position);
-    }
-
-    this(CompileError compileError)
-    {
-        this.result = null;
-        this.error = compileError;
-    }
-
-    @disable this();
-
-    @property bool valid() const
-    {
-        return error.isNull;
-    }
-}
-
-extern(C++, "elna")
-enum Target
-{
-    text,
-    high20,
-    lower12i
-}
-
-extern(C++, "elna")
-struct Reference
-{
-    const(char)* name;
-    size_t offset;
-    Target target;
-}
-
-extern(C++, "elna")
-struct Symbol
-{
-    this(const(char)* name) @nogc;
-    const(char)* name;
-    ubyte* text;
-    size_t length;
-    Reference[3] symbols;
-}
diff --git a/source/lexer.cpp b/source/lexer.cpp
index 00de021..732d63a 100644
--- a/source/lexer.cpp
+++ b/source/lexer.cpp
@@ -1,7 +1,15 @@
 #include "elna/lexer.hpp"
 
+#include <cstring>
+
 namespace elna
 {
+namespace lex
+{
+    using source_position = elna::source::position;
+    using source_error = elna::source::error;
+    using source_result = elna::source::result<std::vector<Token>>;
+
     source::source(const std::string& buffer)
         : m_buffer(buffer)
     {
@@ -14,18 +22,18 @@ namespace elna
 
     source::const_iterator source::end() const
     {
-        Position end_position{ 0, 0 };
+        source_position end_position{ 0, 0 };
 
         return source::const_iterator(std::cend(m_buffer), end_position);
     }
 
     source::const_iterator::const_iterator(std::string::const_iterator buffer,
-            const Position start_position)
+            const source_position start_position)
         : m_buffer(buffer), m_position(start_position)
     {
     }
 
-    const Position& source::const_iterator::position() const noexcept
+    const source_position& source::const_iterator::position() const noexcept
     {
         return this->m_position;
     }
@@ -73,7 +81,7 @@ namespace elna
         return !(*this == that);
     }
 
-    Token::Token(const Type of, const char *value, Position position)
+    Token::Token(const type of, const char *value, source_position position)
         : m_type(of), m_position(position)
     {
         std::size_t value_length = strlen(value);
@@ -85,13 +93,13 @@ namespace elna
         m_value.identifier = buffer;
     }
 
-    Token::Token(const Type of, std::int32_t number, Position position)
+    Token::Token(const type of, std::int32_t number, source_position position)
         : m_type(of), m_position(position)
     {
         m_value.number = number;
     }
 
-    Token::Token(const Type of, Position position)
+    Token::Token(const type of, source_position position)
         : m_type(of), m_position(position)
     {
     }
@@ -110,7 +118,7 @@ namespace elna
 
     Token::~Token()
     {
-        if (m_type == TOKEN_IDENTIFIER || m_type == TOKEN_OPERATOR)
+        if (m_type == type::identifier || m_type == type::term_operator || m_type == type::factor_operator)
         {
             std::free(const_cast<char*>(m_value.identifier));
         }
@@ -120,7 +128,7 @@ namespace elna
     {
         m_type = that.of();
         m_position = that.position();
-        if (that.of() == TOKEN_IDENTIFIER || that.of() == TOKEN_OPERATOR)
+        if (that.of() == type::identifier || that.of() == type::term_operator || m_type == type::factor_operator)
         {
             std::size_t value_length = strlen(that.identifier());
             char *buffer = reinterpret_cast<char *>(malloc(value_length + 1));
@@ -130,7 +138,7 @@ namespace elna
 
             m_value.identifier = buffer;
         }
-        else if (that.of() == TOKEN_NUMBER)
+        else if (that.of() == type::number)
         {
             m_value.number = that.number();
         }
@@ -141,19 +149,19 @@ namespace elna
     {
         m_type = that.of();
         m_position = that.position();
-        if (that.of() == TOKEN_IDENTIFIER || that.of() == TOKEN_OPERATOR)
+        if (that.of() == type::identifier || that.of() == type::term_operator || that.of() == type::factor_operator)
         {
             m_value.identifier = that.identifier();
             that.m_value.identifier = nullptr;
         }
-        else if (that.of() == TOKEN_NUMBER)
+        else if (that.of() == type::number)
         {
             m_value.number = that.number();
         }
         return *this;
     }
 
-    Token::Type Token::of() const noexcept
+    Token::type Token::of() const noexcept
     {
         return m_type;
     }
@@ -168,12 +176,12 @@ namespace elna
         return m_value.number;
     }
 
-    const Position& Token::position() const noexcept
+    const source_position& Token::position() const noexcept
     {
         return m_position;
     }
 
-    Token *lex(const char *buffer, CompileError *compile_error, std::size_t *length)
+    source_result lex(const char *buffer)
     {
         std::vector<Token> tokens;
         source input{ buffer };
@@ -186,38 +194,38 @@ namespace elna
             else if (std::isdigit(*iterator))
             {
                 tokens.emplace_back(
-                        Token::TOKEN_NUMBER,
+                        Token::type::number,
                         static_cast<std::int32_t>(*iterator - '0'),
                         iterator.position()
                 );
             }
             else if (*iterator == '=')
             {
-                tokens.emplace_back(Token::TOKEN_EQUALS, iterator.position());
+                tokens.emplace_back(Token::type::equals, iterator.position());
             }
             else if (*iterator == '(')
             {
-                tokens.emplace_back(Token::TOKEN_LEFT_PAREN, iterator.position());
+                tokens.emplace_back(Token::type::left_paren, iterator.position());
             }
             else if (*iterator == ')')
             {
-                tokens.emplace_back(Token::TOKEN_RIGHT_PAREN, iterator.position());
+                tokens.emplace_back(Token::type::right_paren, iterator.position());
             }
             else if (*iterator == ';')
             {
-                tokens.emplace_back(Token::TOKEN_SEMICOLON, iterator.position());
+                tokens.emplace_back(Token::type::semicolon, iterator.position());
             }
             else if (*iterator == ',')
             {
-                tokens.emplace_back(Token::TOKEN_COMMA, iterator.position());
+                tokens.emplace_back(Token::type::comma, iterator.position());
             }
             else if (*iterator == '!')
             {
-                tokens.emplace_back(Token::TOKEN_BANG, iterator.position());
+                tokens.emplace_back(Token::type::bang, iterator.position());
             }
             else if (*iterator == '.')
             {
-                tokens.emplace_back(Token::TOKEN_DOT, iterator.position());
+                tokens.emplace_back(Token::type::dot, iterator.position());
             }
             else if (std::isalpha(*iterator))
             {
@@ -230,15 +238,15 @@ namespace elna
                 }
                 if (word == "const")
                 {
-                    tokens.emplace_back(Token::TOKEN_LET, iterator.position());
+                    tokens.emplace_back(Token::type::let, iterator.position());
                 }
                 else if (word == "var")
                 {
-                    tokens.emplace_back(Token::TOKEN_VAR, iterator.position());
+                    tokens.emplace_back(Token::type::var, iterator.position());
                 }
                 else
                 {
-                    tokens.emplace_back(Token::TOKEN_IDENTIFIER, word.c_str(), iterator.position());
+                    tokens.emplace_back(Token::type::identifier, word.c_str(), iterator.position());
                 }
                 iterator = i;
                 continue;
@@ -247,24 +255,21 @@ namespace elna
             {
                 std::string _operator{ *iterator };
 
-                tokens.emplace_back(Token::TOKEN_OPERATOR, _operator.c_str(), iterator.position());
+                tokens.emplace_back(Token::type::term_operator, _operator.c_str(), iterator.position());
+            }
+            else if (*iterator == '*' || *iterator == '/')
+            {
+                std::string _operator{ *iterator };
+
+                tokens.emplace_back(Token::type::factor_operator, _operator.c_str(), iterator.position());
             }
             else
             {
-                *compile_error = CompileError("Unexpected next character", iterator.position());
-                return nullptr;
+                return source_result("Unexpected next character", iterator.position());
             }
             ++iterator;
         }
-        Token *target = reinterpret_cast<Token *>(malloc(tokens.size() * sizeof(Token) + sizeof(Token)));
-        int i = 0;
-        for (auto& token : tokens)
-        {
-            target[i] = std::move(token);
-            ++i;
-        }
-        *length = i;
-
-        return target;
+        return source_result(tokens);
     }
 }
+}
diff --git a/source/main.cpp b/source/main.cpp
new file mode 100644
index 0000000..6cd8ba2
--- /dev/null
+++ b/source/main.cpp
@@ -0,0 +1,47 @@
+#include "elna/cl.hpp"
+
+#include <filesystem>
+#include <iostream>
+#include <boost/program_options.hpp>
+
+int main(int argc, char **argv)
+{
+    boost::program_options::options_description visible{ "Allowed options" };
+    boost::program_options::options_description description;
+    boost::program_options::positional_options_description positional;
+    boost::program_options::variables_map variables_map;
+
+    visible.add_options()
+        ("help", "Print this help message")
+        ("output,o", boost::program_options::value<std::filesystem::path>(), "Output object file")
+    ;
+    description.add_options()
+        ("input", boost::program_options::value<std::filesystem::path>()->required())
+    ;
+    description.add(visible);
+    positional.add("input", 1);
+
+    auto parsed = boost::program_options::command_line_parser(argc, argv)
+        .options(description).positional(positional)
+        .run();
+    boost::program_options::store(parsed, variables_map);
+    boost::program_options::notify(variables_map);
+
+    if (variables_map.count("help"))
+    {
+        std::cout << description << std::endl;
+        return 0;
+    }
+    const auto in_file = variables_map["input"].as<std::filesystem::path>();
+    std::filesystem::path out_file;
+
+    if (variables_map.count("output"))
+    {
+        out_file = variables_map["output"].as<std::filesystem::path>();
+    }
+    else
+    {
+        out_file = in_file.filename().replace_extension(".o");
+    }
+    return elna::compile(in_file, out_file);
+}
diff --git a/source/main.d b/source/main.d
deleted file mode 100644
index 3bd823b..0000000
--- a/source/main.d
+++ /dev/null
@@ -1,15 +0,0 @@
-import elna.backend;
-import std.path;
-import std.sumtype;
-import tanya.container.string;
-import tanya.memory.allocator;
-import tanya.memory.mmappool;
-
-extern(C)
-int main(int argc, char** args)
-{
-    defaultAllocator = MmapPool.instance;
-
-    // return generate(args[3], args[2]);
-    return compile(args[3], args[2]);
-}
diff --git a/source/parser.cpp b/source/parser.cpp
index 699a9ee..094a405 100644
--- a/source/parser.cpp
+++ b/source/parser.cpp
@@ -40,17 +40,22 @@ namespace elna
         this->lhs = lhs;
         this->rhs = rhs;
 
-        if (_operator == '+')
+        switch (_operator)
         {
-            this->_operator = BinaryOperator::sum;
-        }
-        else if (_operator == '-')
-        {
-            this->_operator = BinaryOperator::subtraction;
-        }
-        else
-        {
-            throw std::logic_error("Invalid binary operator");
+            case '+':
+                this->_operator = BinaryOperator::sum;
+                break;
+            case '-': 
+                this->_operator = BinaryOperator::subtraction;
+                break;
+            case '*':
+                this->_operator = BinaryOperator::multiplication;
+                break;
+            case '/':
+                this->_operator = BinaryOperator::division;
+                break;
+            default:
+                throw std::logic_error("Invalid binary operator");
         }
     }
 
@@ -64,14 +69,14 @@ namespace elna
         visitor->visit(this);
     }
 
-    Block *parse(Token *tokenStream, std::size_t length)
+    Block *parse(lex::Token *tokenStream, std::size_t length)
     {
         return parseBlock(&tokenStream, &length);
     }
 
-    Expression *parseFactor(Token **tokens, size_t *length)
+    Expression *parseFactor(lex::Token **tokens, size_t *length)
     {
-        if ((*tokens)[0].of() == Token::TOKEN_IDENTIFIER)
+        if ((*tokens)[0].of() == lex::Token::type::identifier)
         {
             auto variable = new Variable();
             variable->identifier = (*tokens)[0].identifier();
@@ -79,7 +84,7 @@ namespace elna
             --(*length);
             return variable;
         }
-        else if ((*tokens)[0].of() == Token::TOKEN_NUMBER)
+        else if ((*tokens)[0].of() == lex::Token::Token::type::number)
         {
             auto number = new Number();
             number->value = (*tokens)[0].number();
@@ -87,7 +92,7 @@ namespace elna
             --(*length);
             return number;
         }
-        else if ((*tokens)[0].of() == Token::TOKEN_LEFT_PAREN)
+        else if ((*tokens)[0].of() == lex::Token::type::left_paren)
         {
             ++(*tokens);
             --(*length);
@@ -102,15 +107,29 @@ namespace elna
         return nullptr;
     }
 
-    Expression *parseTerm(Token **tokens, size_t *length)
+    Expression *parseTerm(lex::Token **tokens, size_t *length)
     {
-        return parseFactor(tokens, length);
+        auto lhs = parseFactor(tokens, length);
+        if (lhs == nullptr || *length == 0 || (*tokens)[0].of() != lex::Token::type::factor_operator)
+        {
+            return lhs;
+        }
+        auto _operator = (*tokens)[0].identifier()[0];
+        ++(*tokens);
+        --(*length);
+
+        auto rhs = parseFactor(tokens, length);
+        if (rhs != nullptr)
+        {
+            return new BinaryExpression(lhs, rhs, _operator);
+        }
+        return nullptr;
     }
 
-    Expression *parseExpression(Token **tokens, size_t *length)
+    Expression *parseExpression(lex::Token **tokens, size_t *length)
     {
         auto term = parseTerm(tokens, length);
-        if (term == nullptr || *length == 0 || (*tokens)[0].of() != Token::TOKEN_OPERATOR)
+        if (term == nullptr || *length == 0 || (*tokens)[0].of() != lex::Token::type::term_operator)
         {
             return term;
         }
@@ -122,17 +141,12 @@ namespace elna
 
         if (expression != nullptr)
         {
-            auto binaryExpression = new BinaryExpression(term, expression, _operator);
-
-            return binaryExpression;
-        }
-        else
-        {
-            return nullptr;
+            return new BinaryExpression(term, expression, _operator);
         }
+        return nullptr;
     }
 
-    Definition *parseDefinition(Token **tokens, size_t *length)
+    Definition *parseDefinition(lex::Token **tokens, size_t *length)
     {
         auto definition = new Definition();
         definition->identifier = (*tokens)[0].identifier(); // Copy.
@@ -141,7 +155,7 @@ namespace elna
         ++(*tokens); // Skip the equals sign.
         *length -= 2;
 
-        if ((*tokens)[0].of() == Token::TOKEN_NUMBER)
+        if ((*tokens)[0].of() == lex::Token::type::number)
         {
             auto number = new Number();
             number->value = (*tokens)[0].number();
@@ -153,9 +167,9 @@ namespace elna
         return nullptr;
     }
 
-    Statement *parseStatement(Token **tokens, std::size_t *length)
+    Statement *parseStatement(lex::Token **tokens, std::size_t *length)
     {
-        if ((*tokens)[0].of() == Token::TOKEN_BANG)
+        if ((*tokens)[0].of() == lex::Token::type::bang)
         {
             ++(*tokens);
             --(*length);
@@ -174,7 +188,7 @@ namespace elna
         return nullptr;
     }
 
-    Definition **parseDefinitions(Token **tokens, size_t *length, size_t *resultLength)
+    Definition **parseDefinitions(lex::Token **tokens, size_t *length, size_t *resultLength)
     {
         ++(*tokens); // Skip const.
         --(*length);
@@ -193,11 +207,11 @@ namespace elna
                     realloc(definitions, (*resultLength + 1) * sizeof(Definition*)));
             definitions[(*resultLength)++] = definition;
 
-            if ((*tokens)[0].of() == Token::TOKEN_SEMICOLON)
+            if ((*tokens)[0].of() == lex::Token::type::semicolon)
             {
                 break;
             }
-            if ((*tokens)[0].of() == Token::TOKEN_COMMA)
+            if ((*tokens)[0].of() == lex::Token::type::comma)
             {
                 ++(*tokens);
                 --(*length);
@@ -207,10 +221,10 @@ namespace elna
         return definitions;
     }
 
-    Block *parseBlock(Token **tokens, std::size_t *length)
+    Block *parseBlock(lex::Token **tokens, std::size_t *length)
     {
         auto block = new Block();
-        if ((*tokens)[0].of() == Token::TOKEN_LET)
+        if ((*tokens)[0].of() == lex::Token::type::let)
         {
             size_t length_ = 0;
             auto constDefinitions = parseDefinitions(tokens, length, &length_);
diff --git a/source/result.cpp b/source/result.cpp
index a65e55f..15fc56a 100644
--- a/source/result.cpp
+++ b/source/result.cpp
@@ -2,26 +2,29 @@
 
 namespace elna
 {
-    CompileError::CompileError(const char *message, const Position position) noexcept
+namespace source
+{
+    error::error(const char *message, const source::position position) noexcept
     {
         this->message = message;
         this->position = position;
     }
 
-    char const *CompileError::what() const noexcept
+    char const *error::what() const noexcept
     {
         return this->message;
     }
 
-    std::size_t CompileError::line() const noexcept
+    std::size_t error::line() const noexcept
     {
         return this->position.line;
     }
 
-    std::size_t CompileError::column() const noexcept
+    std::size_t error::column() const noexcept
     {
         return this->position.column;
     }
+}
 
     Symbol::Symbol(const char *name)
     {
diff --git a/source/riscv.cpp b/source/riscv.cpp
index ac1787a..c2bf3cc 100644
--- a/source/riscv.cpp
+++ b/source/riscv.cpp
@@ -1,7 +1,7 @@
 #include "elna/parser.hpp"
 #include "elna/riscv.hpp"
 #include <memory>
-#include <type_traits>
+#include <cstring>
 
 namespace elna
 {
@@ -49,9 +49,14 @@ namespace elna
         return *this;
     }
 
-    std::uint8_t *Instruction::encode()
+    const std::byte *Instruction::cbegin()
     {
-        return reinterpret_cast<std::uint8_t *>(&this->instruction);
+        return reinterpret_cast<std::byte *>(&this->instruction);
+    }
+
+    const std::byte *Instruction::cend()
+    {
+        return reinterpret_cast<std::byte *>(&this->instruction) + sizeof(this->instruction);
     }
 
     void RiscVVisitor::visit(Node *)
@@ -154,7 +159,7 @@ namespace elna
         std::size_t i = 0;
         for (; i < constCount; ++i)
         {
-            if (strcmp(variable->identifier, constNames[i]) == 0)
+            if (std::strcmp(variable->identifier, constNames[i]) == 0)
             {
                 break;
             }
@@ -218,6 +223,10 @@ namespace elna
                 this->instructions[instructionsLength - 1] = Instruction(BaseOpcode::op)
                     .r(lhs_register, Funct3::sub, XRegister::a0, XRegister::t0, Funct7::sub);
                 break;
+            case BinaryOperator::multiplication:
+                this->instructions[instructionsLength - 1] = Instruction(BaseOpcode::op)
+                    .r(lhs_register, Funct3::mul, XRegister::a0, XRegister::t0, Funct7::muldiv);
+                break;
         }
     }
 
@@ -232,11 +241,10 @@ namespace elna
         {
             program.symbols[i] = visitor->references[i];
         }
-        program.text = reinterpret_cast<unsigned char *>(malloc(sizeof(std::uint32_t) * visitor->instructionsLength));
         for (std::size_t i = 0; i < visitor->instructionsLength; ++i)
         {
-            memcpy(program.text + program.length, visitor->instructions[i].encode(), sizeof(std::uint32_t));
-            program.length += sizeof(std::uint32_t);
+            program.text.insert(program.text.cend(),
+                    visitor->instructions[i].cbegin(), visitor->instructions[i].cend());
         }
         return program;
     }
diff --git a/tests/expectations/multiply.txt b/tests/expectations/multiply.txt
new file mode 100644
index 0000000..f599e28
--- /dev/null
+++ b/tests/expectations/multiply.txt
@@ -0,0 +1 @@
+10
diff --git a/tests/multiply.eln b/tests/multiply.eln
new file mode 100644
index 0000000..b6aef9d
--- /dev/null
+++ b/tests/multiply.eln
@@ -0,0 +1 @@
+! 5 * 2
diff --git a/tests/runner.cpp b/tests/runner.cpp
index 27c6052..bd9eadf 100755
--- a/tests/runner.cpp
+++ b/tests/runner.cpp
@@ -35,9 +35,14 @@ namespace elna
         }
     }
 
+    static std::filesystem::path in_build_directory()
+    {
+        return "build/riscv";
+    }
+
     static std::string in_build_directory(const std::filesystem::path& path)
     {
-        return "build/riscv" / path;
+        return in_build_directory() / path;
     }
 
     static int build_test(const std::filesystem::directory_entry& test_entry)
@@ -136,7 +141,7 @@ namespace elna
 
 int main()
 {
-    boost::process::system("rake");
+    std::filesystem::create_directory(elna::in_build_directory());
 
     std::cout << "Run all tests and check the results" << std::endl;
     std::filesystem::path test_directory{ "tests" };