Compile-Time Expressions

Compile-Time Expressions

One of HolyC's most distinctive features is #exe — a block that runs during compilation, not at runtime. In TempleOS, the compiler and runtime share the same environment, so this boundary is unusually thin.

The #exe Block

#exe {
  Print("This runs at compile time!\n");
  I64 x = 6 * 7;
  // x is now available as a compile-time constant
}

When the compiler encounters a #exe block, it immediately executes its contents. Output appears before the program "starts". This replaces C's #define macros with actual executable code.

Compute Constants at Compile Time

I64 BUFFER_SIZE;
#exe { BUFFER_SIZE = 1024; }

Print("Buffer: %d bytes\n", BUFFER_SIZE);

This is more powerful than #define because any arbitrary logic can run at compile time:

I64 MAX_PRIMES;
#exe {
  MAX_PRIMES = 0;
  for (I64 i = 2; i < 100; i++) {
    Bool prime = TRUE;
    for (I64 j = 2; j < i; j++) {
      if (i % j == 0) { prime = FALSE; }
    }
    if (prime) MAX_PRIMES++;
  }
}
Print("Primes below 100: %d\n", MAX_PRIMES);

No #define

HolyC intentionally omits the C preprocessor's #define. All metaprogramming is done through #exe and HolyC's direct compiler access. This makes metaprogramming a first-class concept rather than a text-substitution hack.

Your Task

Use #exe to compute 6 * 7 into a variable ANSWER at compile time. Then print it at runtime.

Expected output: The answer is 42