🕸Fergus Duniho wrote on Sun, Nov 17, 2019 01:36 AM UTC:
I don't know exactly what the issue is (and there could be more than one) but part of it seems to revolve around the fact that the rules for Bishop moves are complicated, and I've codified them nicely in subroutines "B" and "b", but the architecture seems to want the 1-line fn defs, which don't seem to support if-then-else, and my attempts to have a def B pass off to a gosub B doesn't seem to work either.
I tried out your Symmetric Chess preset. The conversion rule seems to be enforced correctly, but conversion moves are not displaying as legal moves, and when a Bishop must convert, it is incorrectly displaying illegal moves as legal. As you correctly surmise, this is because you do not have the b and B functions defined.
While functions do not support if-then-else, as such, they do support cond, which works like the ? and : operators.They can also use and, or, nand, nor, onlyif, and unless. You can look at the functions for other divergent pieces, such as the Pawn or the Cannon, for examples of how to handle this. Here are some examples from chess3. If you understand the logic behind these, you should be able to figure out how to handle the Bishops conversion rule.
def P
remove var ep
and < rankname #1 var bpr
and < rankname var ep rankname #1
and == filename var ep filename #1
and checkleap #0 #1 1 1
or and checkride #0 #1 0 1 == rankname #0 var wpr
or checkleap #0 #1 0 1
and empty #1
or and islower space #1 checkleap #0 #1 1 1
and <= distance #0 #1 var fps
and > rank #1 rank #0;
Remember that Game Courier evaluates functions from right to left, and many of the logical operators will work with either one or two operands. In the Pawn example, the logical operators are normally taking only one operand. When and receives a lone true value, it lets the function continue silently, but if it receives a false value, it returns a false value and exits. When or receives a lone false value, it lets the function continue silently, but if it receives a true value, it returns a true value and exits. If you still need more help, just ask.
I tried out your Symmetric Chess preset. The conversion rule seems to be enforced correctly, but conversion moves are not displaying as legal moves, and when a Bishop must convert, it is incorrectly displaying illegal moves as legal. As you correctly surmise, this is because you do not have the b and B functions defined.
While functions do not support if-then-else, as such, they do support cond, which works like the ? and : operators. They can also use and, or, nand, nor, onlyif, and unless. You can look at the functions for other divergent pieces, such as the Pawn or the Cannon, for examples of how to handle this. Here are some examples from chess3. If you understand the logic behind these, you should be able to figure out how to handle the Bishops conversion rule.
def C cond cond empty #0 capture (not empty #1) (checkhop #0 #1 0 1) (checkride #0 #1 0 1) and #1;
def P
remove var ep
and < rankname #1 var bpr
and < rankname var ep rankname #1
and == filename var ep filename #1
and checkleap #0 #1 1 1
or and checkride #0 #1 0 1 == rankname #0 var wpr
or checkleap #0 #1 0 1
and empty #1
or and islower space #1 checkleap #0 #1 1 1
and <= distance #0 #1 var fps
and > rank #1 rank #0;
Remember that Game Courier evaluates functions from right to left, and many of the logical operators will work with either one or two operands. In the Pawn example, the logical operators are normally taking only one operand. When and receives a lone true value, it lets the function continue silently, but if it receives a false value, it returns a false value and exits. When or receives a lone false value, it lets the function continue silently, but if it receives a true value, it returns a true value and exits. If you still need more help, just ask.