diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..713001d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+.sw*
+main
diff --git a/LICENSE b/LICENSE
index d41c0bd..847984e 100644
--- a/LICENSE
+++ b/LICENSE
@@ -200,33 +200,3 @@ IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY C
 17. Interpretation of Sections 15 and 16.
 If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.
 
-END OF TERMS AND CONDITIONS
-
-How to Apply These Terms to Your New Programs
-
-If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
-
-To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
-
-     <one line to give the program's name and a brief idea of what it does.>
-     Copyright (C) <year>  <name of author>
-
-     This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
-
-     This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
-
-     You should have received a copy of the GNU General Public License along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-Also add information on how to contact you by electronic and paper mail.
-
-If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
-
-     <program>  Copyright (C) <year>  <name of author>
-     This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
-     This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details.
-
-The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an “about box”.
-
-You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see <http://www.gnu.org/licenses/>.
-
-The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read <http://www.gnu.org/philosophy/why-not-lgpl.html>.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..1978ffb
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,8 @@
+#CXX := clang++-19
+CXXFLAGS += -O0 -std=c++23 -Wall -Wextra -Wpedantic -ggdb -g3
+
+all: main
+
+clean:
+	rm -f main
+
diff --git a/core.fth b/core.fth
new file mode 100644
index 0000000..69ce9a2
--- /dev/null
+++ b/core.fth
@@ -0,0 +1,41 @@
+: cell      8 ;
+: cell+     cell + ;
+: cells     cell * ;
+: char+     1 + ;
+: chars     ;
+
+: state     _d 7 cells + ;
+: [         0 state ! ; immediate
+: ]         -1 state ! ;
+
+: sp        _d ;
+: rp        [ _d cell+ ] literal ;
+: dp        [ _d 3 cells + ] literal ;
+
+: sp@       sp @ ;
+: rp@       rp @ cell+ ;
+: ip        [ _d cell+ cell+ ] literal ;
+: here      dp @ ;
+: unused    [ _d 8 cells + ] literal @ here - ;
+: latest    [ _d 4 cells + ] literal @ ;
+
+: dup       sp@ @ ;
+: drop      sp@ cell+ sp ! ;
+: pick      cells cell+ sp@ + @ ;
+: >r        rp@ cell - rp !
+            rp@ cell+ @ rp@ !
+            rp@ cell+ ! ;
+: r>        rp@ @
+            rp@ cell+ rp !
+            rp@ @ swap rp@ ! ;
+: rot       >r swap r> swap ;
+: -rot      rot rot ;
+: over      1 pick ;
+
+: +!        dup >r swap r> @ + swap ! ;
+: allot     dp +! ;
+: ,         here ! cell allot ;
+
+: 1+        1 + ;
+: 1-        1 - ;
+
diff --git a/forth.hpp b/forth.hpp
new file mode 100644
index 0000000..c19c24e
--- /dev/null
+++ b/forth.hpp
@@ -0,0 +1,320 @@
+/// sforth, an implementation of forth
+/// Copyright (C) 2024  Clyne Sullivan <clyne@bitgloo.com>
+///
+/// This program is free software: you can redistribute it and/or modify it
+/// under the terms of the GNU General Public License as published by the Free
+/// Software Foundation, either version 3 of the License, or (at your option)
+/// any later version.
+///
+/// This program is distributed in the hope that it will be useful, but WITHOUT
+/// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+/// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+/// more details.
+///
+/// You should have received a copy of the GNU General Public License along
+/// with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef SFORTH_HPP
+#define SFORTH_HPP
+
+#include <algorithm>
+#include <array>
+#include <charconv>
+#include <cstdint>
+#include <cstddef>
+#include <iterator>
+#include <span>
+#include <string_view>
+#include <tuple>
+#include <utility>
+
+struct forth
+{
+    using cell = std::intptr_t;
+    using addr = std::uintptr_t;
+    using func = void (*)(void *);
+
+    static constexpr bool enable_exceptions = true;
+    static constexpr int data_size = 16;
+    static constexpr int return_size = 16;
+
+    static constexpr auto npos = std::string_view::npos;
+
+    enum class error {
+        init_error,
+        parse_error,
+        execute_error,
+        dictionary_overflow,
+        word_not_found,
+        stack_underflow,
+        stack_overflow,
+        return_stack_underflow,
+        return_stack_overflow,
+        compile_only_word
+    };
+
+    template<error Err>
+    static inline void assert(bool condition) {
+        if constexpr (enable_exceptions) {
+            if (!condition)
+                throw Err;
+        }
+    }
+
+    struct word_base {
+        static constexpr addr immediate = 1 << 8;
+
+        word_base *next;
+        addr flags_len;
+
+        auto name() const -> std::string_view {
+            return {reinterpret_cast<const char *>(this + 1)};
+        }
+
+        auto body() -> func * {
+            auto ptr = reinterpret_cast<std::uint8_t *>(this + 1) + (flags_len & 0xFF);
+            return reinterpret_cast<func *>(ptr);
+        }
+    };
+
+    void push(cell v) {
+        assert<error::stack_overflow>(sp != dstack.begin());
+        *--sp = v;
+    }
+
+    void push(cell v, auto... vs) {
+        push(v); (push(vs), ...);
+    }
+
+    void rpush(func *v) {
+        assert<error::return_stack_overflow>(rp != rstack.begin());
+        *--rp = reinterpret_cast<cell>(v);
+    }
+
+    cell& top() {
+        assert<error::stack_underflow>(sp != dstack.end());
+        return *sp;
+    }
+
+    cell pop() {
+        assert<error::stack_underflow>(sp != dstack.end());
+        auto ret = *sp;
+        *sp++ = -1;
+        return ret;//*sp++;
+    }
+
+    auto rpop() -> func * {
+        assert<error::return_stack_underflow>(rp != rstack.end());
+        auto ret = reinterpret_cast<func *>(*rp);
+        *rp++ = -1;
+        return ret;
+    }
+
+    template<int N>
+    auto pop() {
+        static_assert(N > 0, "pop<N>() with N <= 0");
+
+        auto t = std::tuple {pop()};
+        if constexpr (N > 1)
+            return std::tuple_cat(t, pop<N - 1>());
+        else
+            return t;
+    }
+
+    forth& add(std::string_view name, func entry = nullptr) {
+        const auto namesz = (name.size() + 1 + sizeof(cell)) & ~(sizeof(cell) - 1);
+        const auto size = (sizeof(word_base) + namesz) / sizeof(cell);
+
+        assert<error::parse_error>(!name.empty());
+        //assert<error::dictionary_overflow>(state->here + size < &dictionary.back());
+
+        const auto h = std::exchange(here, here + size);
+        auto w = new (h) word_base (nullptr, namesz);
+        w->next = std::exchange(latest, w);
+        std::copy(name.begin(), name.end(),
+            reinterpret_cast<char *>(h) + sizeof(word_base));
+        if (entry)
+            *here++ = reinterpret_cast<cell>(entry);
+        return *this;
+    }
+
+    forth& make_immediate() {
+        latest->flags_len |= word_base::immediate;
+        return *this;
+    }
+
+    void parse_line(std::string_view sv) {
+        source = sv.data();
+        sourcei = sv.find_first_not_of(" \t\r\n");
+
+        while (sourcei != npos) {
+            const auto word = parse();
+
+            if (auto ent = get(word); !ent) {
+                cell n;
+                const auto [p, e] = std::from_chars(word.cbegin(), word.cend(), n);
+
+                assert<error::word_not_found>(e == std::errc() && p == word.cend());
+
+                push(n);
+
+                if (compiling)
+                    execute((*get("literal"))->body());
+            } else {
+                auto body = (*ent)->body();
+
+                if (compiling && ((*ent)->flags_len & word_base::immediate) == 0) {
+                    *here++ = reinterpret_cast<cell>(body);
+                } else {
+                    execute(body);
+                }
+            }
+        }
+    }
+
+    auto parse() -> std::string_view {
+        const std::string_view sv {source};
+
+        const auto e = sv.find_first_of(" \t\r\n", sourcei);
+        const auto word = e != npos ? sv.substr(sourcei, e - sourcei)
+                                    : sv.substr(sourcei);
+    
+        sourcei = sv.find_first_not_of(" \t\r\n", e);
+        return word;
+    }
+
+    void execute(func *body) {
+        assert<error::execute_error>(body && *body);
+        (*body)(body);
+    }
+
+    auto get(std::string_view sv) -> std::optional<word_base *> {
+        for (auto lt = latest; lt; lt = lt->next) {
+            if (sv == lt->name())
+                return lt;
+        }
+
+        return {};
+    }
+
+    template<forth **fthp>
+    static void prologue(func *body) {
+        static auto& fth = **fthp;
+
+        fth.rpush(fth.ip);
+
+        for (fth.ip = body + 1; *fth.ip; fth.ip++)
+            fth.execute(reinterpret_cast<func *>(*fth.ip));
+
+        fth.ip = fth.rpop();
+    }
+
+    template<forth** fthp>
+    static void initialize(cell *end_value)
+    {
+        assert<error::init_error>(*fthp);
+
+        static auto& fth = **fthp;
+
+        fth.end = end_value;
+        fth
+            .add("_d", [](auto) { fth.push(reinterpret_cast<cell>(&fth)); })
+            //.add("[",    [](auto) { fth.compiling = false; }).make_immediate()
+            //.add("]",    [](auto) { fth.compiling = true; })
+            .add("immediate", [](auto) { fth.make_immediate(); }).make_immediate()
+            .add("literal", [](auto) {
+                static auto lit_impl = +[] {
+                    auto ptr = reinterpret_cast<cell *>(++fth.ip);
+                    fth.push(*ptr);
+                };
+                assert<error::compile_only_word>(fth.compiling);
+                *fth.here++ = reinterpret_cast<cell>(&lit_impl);
+                *fth.here++ = fth.pop();
+            }).make_immediate()
+            .add("@",    [](auto) { fth.push(*reinterpret_cast<cell *>(fth.pop())); })
+            .add("!",    [](auto) {
+                auto [p, v] = fth.pop<2>();
+                *reinterpret_cast<cell *>(p) = v; })
+            .add("swap", [](auto) { auto [a, b] = fth.pop<2>(); fth.push(a, b); })
+            //.add("drop", [](auto) { fth.pop(); })
+            //.add("dup",  [](auto) { fth.push(fth.top()); })
+            //.add("rot",  [](auto) { auto [a, b, c] = fth.pop<3>(); fth.push(b, a, c); })
+            .add("+",    [](auto) { fth.top() += fth.pop(); })
+            .add("-",    [](auto) { fth.top() -= fth.pop(); })
+            .add("*",    [](auto) { fth.top() *= fth.pop(); })
+            .add("/",    [](auto) { fth.top() /= fth.pop(); })
+            .add("and",  [](auto) { fth.top() &= fth.pop(); })
+            .add("or",   [](auto) { fth.top() |= fth.pop(); })
+            .add("xor",  [](auto) { fth.top() ^= fth.pop(); })
+            .add("=",    [](auto) { auto v = fth.pop(); fth.top() = -(fth.top() == v); })
+            .add("<",    [](auto) { auto v = fth.pop(); fth.top() = -(fth.top() < v); })
+            .add("\'", [](auto) {
+                auto w = fth.parse();
+
+                if (auto g = fth.get(w); g)
+                    fth.push(reinterpret_cast<cell>((*g)->body()));
+                else
+                    fth.push(0);
+            })
+            .add(":", [](auto) {
+                auto w = fth.parse();
+                fth.add(w);
+                *fth.here++ = reinterpret_cast<cell>(forth::prologue<fthp>);
+                fth.compiling = true;
+            })
+            .add(";", [](auto) {
+                *fth.here++ = 0;
+                fth.compiling = false;
+            }).make_immediate()
+            .add("\\", [](auto) {
+                fth.sourcei = npos;
+            }).make_immediate();
+    }
+
+    static auto error_string(error err) noexcept -> std::string_view {
+        using enum error;
+        switch (err) {
+        case init_error:             return "init error";
+        case parse_error:            return "parse error";
+        case execute_error:          return "execute error";
+        case dictionary_overflow:    return "dictionary overflow";
+        case word_not_found:         return "word not found";
+        case stack_underflow:        return "stack underflow";
+        case stack_overflow:         return "stack overflow";
+        case return_stack_underflow: return "return stack underflow";
+        case return_stack_overflow:  return "return stack overflow";
+        case compile_only_word:      return "compile only word";
+        default:                     return "unknown error";
+        }
+    }
+
+    constexpr forth() {
+        sp = dstack.end();
+        rp = rstack.end();
+    }
+
+    cell *sp;
+    cell *rp;
+    func *ip = nullptr;
+    cell *here = reinterpret_cast<cell *>(this + 1);
+    word_base *latest = nullptr;
+    const char *source = nullptr;
+    std::size_t sourcei = npos;
+    cell compiling = false;
+    cell *end = nullptr;
+    std::array<cell, data_size> dstack;
+    std::array<cell, return_size> rstack;
+};
+
+static_assert(offsetof(forth::word_base, flags_len) == 1 * sizeof(forth::cell));
+static_assert(offsetof(forth, rp)        == 1 * sizeof(forth::cell));
+static_assert(offsetof(forth, ip)        == 2 * sizeof(forth::cell));
+static_assert(offsetof(forth, here)      == 3 * sizeof(forth::cell));
+static_assert(offsetof(forth, latest)    == 4 * sizeof(forth::cell));
+static_assert(offsetof(forth, source)    == 5 * sizeof(forth::cell));
+static_assert(offsetof(forth, sourcei)   == 6 * sizeof(forth::cell));
+static_assert(offsetof(forth, compiling) == 7 * sizeof(forth::cell));
+static_assert(offsetof(forth, end)       == 8 * sizeof(forth::cell));
+
+#endif // SFORTH_HPP
+
diff --git a/main.cpp b/main.cpp
new file mode 100644
index 0000000..d9cb5c5
--- /dev/null
+++ b/main.cpp
@@ -0,0 +1,70 @@
+/// sforth, an implementation of forth
+/// Copyright (C) 2024  Clyne Sullivan <clyne@bitgloo.com>
+///
+/// This program is free software: you can redistribute it and/or modify it
+/// under the terms of the GNU General Public License as published by the Free
+/// Software Foundation, either version 3 of the License, or (at your option)
+/// any later version.
+///
+/// This program is distributed in the hope that it will be useful, but WITHOUT
+/// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+/// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+/// more details.
+///
+/// You should have received a copy of the GNU General Public License along
+/// with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "forth.hpp"
+
+#include <array>
+#include <fstream>
+#include <iostream>
+#include <span>
+#include <string>
+
+static std::array<forth::cell, 1024> dict;
+static auto fth = new (dict.data()) forth;
+
+static bool parse_stream(forth *, std::istream&, bool say_okay = false);
+
+int main(int argc, const char *argv[])
+{
+    std::span args (argv + 1, argc - 1);
+
+    forth::initialize<&fth>(dict.end());
+    fth->add(".", [](auto) { std::cout << fth->pop() << ' '; });
+    fth->add("emit", [](auto) { std::cout << static_cast<char>(fth->pop()); });
+
+    for (auto arg : args) {
+        if (std::ifstream file {arg}; parse_stream(fth, file))
+            return 0;
+    }
+
+    parse_stream(fth, std::cin, true);
+}
+
+bool parse_stream(forth *fth, std::istream& str, bool say_okay)
+{
+    std::string line;
+
+    while (str.good()) {
+        std::getline(str, line);
+        if (!line.empty()) {
+            if (line == "bye")
+                return true;
+
+            try {
+                fth->parse_line(line);
+            } catch (forth::error e) {
+                std::cerr << fth->error_string(e);
+                continue;
+            }
+        }
+
+        if (say_okay)
+            std::cout << (fth->compiling ? "compiled" : "ok") << std::endl;
+    }
+
+    return false;
+}
+