Add C++ language

2 files changed, 80 insertions, 0 deletions

diff --git a/languages/c/c++/README.md b/languages/c/c++/README.md
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+# C++ Lambda Core
+
+## Requirements
+
+- GCC 14 or above
+
+## Compile and run
+
+```sh
+g++ lambda-core.cpp -std=c++23 -o app
+./app
+```
+
diff --git a/languages/c/c++/lambda-core.cpp b/languages/c/c++/lambda-core.cpp
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index 0000000..3c1ae20
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+++ b/languages/c/c++/lambda-core.cpp
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+#include <print>
+
+namespace logic {
+constexpr auto _true = [](const auto &x) {
+  return [&x](const auto &) { return x; };
+};
+
+constexpr auto _false = [](const auto &) {
+  return [](const auto &y) { return y; };
+};
+
+constexpr auto _not = [](const auto &x) { return x(_false)(_true); };
+
+constexpr auto _and = [](const auto &x) {
+  return [&x](const auto &y) { return x(y)(_false); };
+};
+
+constexpr auto _or = [](const auto &x) {
+  return [&x](const auto &y) { return x(_true)(y); };
+};
+
+namespace test {
+constexpr bool convert(const auto &x) { return x(true)(false); }
+
+void print(const auto &x) { std::println("{}", convert(x)); }
+} // namespace test
+} // namespace logic
+
+namespace church {
+constexpr auto zero = [](const auto &) {
+  return [](const auto &x) { return x; };
+};
+
+constexpr auto succ = [](const auto &n) {
+  return [&n](const auto &f) {
+    return [&n, &f](const auto &x) { return f(n(f)(x)); };
+  };
+};
+
+constexpr auto one = succ(zero);
+
+namespace test {
+constexpr unsigned int convert(const auto &n) {
+  return n([](const auto &x) { return x + 1; })(0);
+}
+
+void print(const auto &n) { std::println("{}", convert(n)); }
+} // namespace test
+} // namespace church
+
+int main() {
+  using namespace logic;
+  using namespace church;
+
+  static_assert(logic::test::convert(_true) == true);
+  static_assert(logic::test::convert(_false) == false);
+  static_assert(logic::test::convert(_and(_true)(_true)) == true);
+  static_assert(logic::test::convert(_and(_true)(_false)) == false);
+  static_assert(logic::test::convert(_or(_true)(_true)) == true);
+  static_assert(logic::test::convert(_or(_true)(_false)) == true);
+  logic::test::print(_true);
+
+  static_assert(church::test::convert(zero) == 0);
+  static_assert(church::test::convert(succ(zero)) == 1);
+  // static_assert(church::test::convert(pred(succ(one))) == 1);
+  church::test::print(one);
+}