Minimal Lua5.1 test app for POSIX (compiled size on x64 Debian is ~130 KB with static Lua, dynamic libc/libm)

lua-repl.c

#include <stdio.h>
#include <stdlib.h>
#include <lua.h>
#include <lauxlib.h>

int main()
{
	lua_State* L = luaL_newstate();
	char* line = NULL;
	size_t n = 0;

	for (;;) {
		if (getline(&line, &n, stdin) <= 1) {
			break;
		}

		luaL_dostring(L, line);
		printf("> %s\n", lua_tostring(L, -1));
	}

	free(line);
	lua_close(L);

	return 0;
}