diff --git a/lean/Makefile b/lean/Makefile
index 2ab6ad0..d09401b 100644
--- a/lean/Makefile
+++ b/lean/Makefile
@@ -4,8 +4,8 @@
 
 test:
 	gcc -c src/*.c -Iinclude -Wall -pedantic --std=gnu11
-	g++ -c src/*.cpp -Iinclude -Wall -pedantic --std=gnu++11
-	gcc -o $@ *.o
+	g++ -c src/*.cpp -Iinclude -Wall -pedantic --std=gnu++20
+	g++ -o $@ *.o
 	./$@
 clean:
 	rm -f test
diff --git a/lean/include/map.h b/lean/include/map.h
index 7574cf2..87534a1 100644
--- a/lean/include/map.h
+++ b/lean/include/map.h
@@ -18,8 +18,52 @@ typedef struct mmap {
 int open_and_map(const char* file, mmap_t* restrict ptr);
 int unmap_and_close(mmap_t map);
 
-#ifdef _cplusplus
+typedef void* (*map_cb)(mmap_t map);
+void* map_and_then(const char* file, map_cb callback);
+
+#ifdef __cplusplus
+}
+#include <panic.h>
+#include <cstdint>
+namespace mm {
+	struct mmap {
+		inline static mmap_t create_raw(const char* file)
+		{
+			mmap_t map;
+			if (!open_and_map(file, &map)) panic("Failed to map file");
+			return map;
+		}
+
+		inline mmap(mmap_t raw) :inner(raw){}
+		inline mmap(const char* file)
+			: inner(create_raw(file)) {}
+
+		inline mmap(mmap&& move) : inner(move.inner)
+		{
+			auto other = const_cast<mmap_t*>(&move.inner);
+			other->ptr = nullptr;
+		}
+		inline mmap(const mmap& copt) = delete;
+
+		inline ~mmap()
+		{
+			if (inner.ptr) {
+				::unmap_and_close(inner);
+			}
+		}
+
+		inline const std::uint8_t* as_ptr() const { return (const std::uint8_t*)inner.ptr; }
+		inline std::uint8_t* as_ptr() { return (std::uint8_t*)inner.ptr; }
+
+		inline std::size_t size() const { return inner.len; }
+
+		inline int as_fd() const { return inner.fd; }
+		inline const mmap_t& as_raw() const { return inner; }
+	private:	
+		const mmap_t inner;
+	};
 }
+
 #undef restrict
 #endif
 
diff --git a/lean/src/main.c b/lean/src/main.c
index 3197400..330c412 100644
--- a/lean/src/main.c
+++ b/lean/src/main.c
@@ -7,6 +7,7 @@
 #include <shuffle3.h>
 #include <panic.h>
 #include <reinterpret.h>
+#include <map.h>
 
 _Static_assert(sizeof(float)==sizeof(uint32_t), "float is not 32 bits");
 
@@ -21,6 +22,14 @@ static void unshuffle_file(const char* filename)
 	panic("unimplemented");
 }*/
 
+static void* map_callback(mmap_t map)
+{
+	printf("fd %d mapped (sz %lu) (ptr %p)\n", map.fd, map.len, map.ptr);	
+
+
+	return NULL;
+}
+
 static void do_test()
 {
 	char* string = "Hello world.. how are you?????";
@@ -45,7 +54,10 @@ static void do_test()
 
 int main(int argc, char** argv)
 {
-	do_test();	
+	do_test();
+	if( argv[1] ) {
+		map_and_then(argv[1], &map_callback);
+	}
 
 	return 0;
 }
diff --git a/lean/src/map_callback.cpp b/lean/src/map_callback.cpp
new file mode 100644
index 0000000..8ea87b8
--- /dev/null
+++ b/lean/src/map_callback.cpp
@@ -0,0 +1,11 @@
+
+#include <shuffle3.h>
+#include <reinterpret.hpp>
+#include <map.h>
+
+
+extern "C" void* map_and_then(const char* file, map_cb callback)
+{
+	mm::mmap map(file);
+	return callback(map.as_raw());
+}