betseg helped imnporeove let and let_mut

main.c

@@ -1,9 +1,8 @@
-#include <stdio.h>
 #include "rust.h"
 
-fn main() {
-   let_mut_int a = 7;
-   print("Hello, World!\n");
+fn(main(), int) {
+   let_mut(a, int) = 7;
    a += 1;
+   print("Hello, World!\n", a);
    Ok();
 }

rust.h

@@ -1,17 +1,14 @@
 #include <stdbool.h>
+#include <stdio.h>
 
-#define fn int
-#define let_int const int
-#define let_float const float
-#define let_bool const bool
-#define let_char const char
 
-#define let_mut_int  int
-#define let_mut_float float
-#define let_mut_bool  bool
-#define let_mut_char  char
+#define fn(decl, type) type decl
+#define let(decl, type) const type decl
+#define let_mut(decl, type) type decl
 
 #define print printf
 #define loop while(true)
 #define Ok(); return 0
 #define Err(); return 1
+
+#define enum union