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0 pointsmartincmartin1y ago0 comments

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.

0 comments

jprete1y ago

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.

martincmartinOP1y ago

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

MarkusQ1y ago

Ah, the old

    My
    Dear
    Aunt
    Sally

vs.

    My Dear
    Aunt Sally

debate. :)

pbhjpbhj1y ago

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.

martincmartinOP1y ago

Thanks. Fixed!

omoikane1y ago

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".

LegionMammal9781y ago

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.

LegionMammal9781y ago

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.)

j / k navigate · click thread line to collapse

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jprete1y ago

martincmartinOP1y ago

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

MarkusQ1y ago

Ah, the old

    My
    Dear
    Aunt
    Sally

vs.

    My Dear
    Aunt Sally

debate. :)

pbhjpbhj1y ago

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.

martincmartinOP1y ago

Thanks. Fixed!

omoikane1y ago

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".

LegionMammal9781y ago

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.

j / k navigate · click thread line to collapse