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Comment by phkahler | Hacker News Reader

I needed to know what language that is written in. Turns out it's something called FOCAL, as mentioned in this article about the game:

https://retro365.blog/2021/12/02/bits-from-my-personal-colle...

Wikipedia on FOCAL:

https://en.wikipedia.org/wiki/FOCAL_(programming_language)

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OP here. One interesting thing about FOCAL is that * has higher precedence than /. So in Lunar Lander, M*G/Z*K is what mathematicians and other languages would write M*G/(Z*K). I did a double take when I first saw that. :) As the Wikipedia article says, "This can cause subtle errors when converting FOCAL source code to other systems."

Also, the IF syntax is a little limiting and hard to read, although I suppose programmers would get used to it.

That's surprising from today's perspective, but when I imagine the thought process, it seems reasonable, especially for math and science purposes where multiplication and division operators usually get grouped into a series of multiplications above the division bar, and a series of multiplications below it.

True. + also has higher precedence than -, so that a - b + c means a - (b + c).

Ah, the old

    My
    Dear
    Aunt
    Sally

vs.

    My Dear
    Aunt Sally

debate. :)

Your code got munged, use backslash to escape * (otherwise it starts a span of italicised text), or use four leading blanks for code blocks (in which escaping is usually not needed):

M*G/Z*K

I think you meant, the above and

    M*G/(Z*K)

respectively.

Thanks. Fixed!

Another curious feature is that the labels appears to be floating point, as in "G 5.9" appears to transfer control to line starting at "05.90".

They aren't actually floating-point: each label is a pair of numbers, the first denoting the group and the second denoting the line within that group. The groups have no semantic importance, they are only for organization.

Actually, I was mistaken. The line numbers aren't even numbers, so much as digit pairs, given how one-digit labels take the first digit.

And the "DO" command takes a group number, runs each line within the group, then returns after the end of the group. So each group can effectively act as a subroutine. (In this particular game, this can be seen in groups 6 and 9.)

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