On: Show HN: 3D shooter in your terminal using raycast...

[Stratoscope]

That is brilliant!

So the embedded FORTH compiler written in AWK reads the FORTH code in a comment like this:

  //@C SPACES
  // \ n --
  //   BEGIN
  //     DUP 0>
  //   WHILE
  //     SPACE 1-
  //   REPEAT
  //   DROP

and compiles it into C code like this (reformatted here to help illustrate):

  COM(
      spaces_word, codeword, "SPACES", &space_word,
          (void*)&dup_word, (void*)&more0_word,
      (void*)&branch0_word, (void*)(&spaces_word.payload[0] + 8),
          (void*)&space_word, (void*)&sub_one_word,
      (void*)&branch_word, (void*)(&spaces_word.payload[0] + 0),
      (void*)&drop_word,
      (void*)&exit_word
  )

[david-given → Stratoscope]

Yup! COM() is a varargs macro that actually assembles the data in memory --- the actual word layout is not the traditional one Forth uses (to make it C friendly). But the end result is a linked list of Forth words in exactly the same format that user words have, which the user dictionary extends.

It all means that the C source can just be compiled in a single step --- gcc -o fforth fforth.c --- without needing a precompilation stage, which makes it vastly easier to manage.

It's even portable!