73 lines
2.8 KiB
Scheme
73 lines
2.8 KiB
Scheme
; a helper function which prints each argument seperated by a space
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(define output
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(lambda (. things)
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(cond
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((null? things) (display #\newline))
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(else
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(display (car things))
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(display #\space)
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(apply output (cdr things))))))
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; a helper function which shows arguments before calling them
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(define explicit-apply
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(lambda (f . args)
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(let ((result (apply f args)))
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(output f args result)
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result)))
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; determine whether or not a given attack roll will hit
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(define is-hit?
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(lambda (roll attack ac)
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(or (= roll 20) (and (< 1 roll) (>= (+ roll attack) ac)))))
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; determine whether or not a given attack roll will crit
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(define is-crit?
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(lambda (roll attack ac threat)
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(or (= roll 20) (and (is-hit? roll attack ac) (>= roll threat)))))
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; determine the expected damage of a particular attack roll
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(define roll-dmg
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(lambda (roll attack ac dmg threat mult)
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(cond
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((is-crit? roll attack ac threat) (* dmg mult))
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((is-hit? roll attack ac) dmg)
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(else 0))))
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; determine the expected damage across all attack rolls
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(define expected-dmg
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(lambda (. args)
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(define adder
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(lambda (total roll)
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(if (> roll 20)
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total
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(adder (+ total (apply roll-dmg roll args))
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(+ roll 1)))))
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(/ (adder 0 1) 20)))
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; find the best power attack score (and expected damage) versus an AC
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(define find-best-power
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(lambda (power-max attack ac dmg threat mult)
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(define checker
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(lambda (power best-power best-dmg)
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(if (> power power-max)
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(list best-power best-dmg)
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(let* ((a (- attack power))
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(d (+ dmg power))
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(ed (expected-dmg a ac d threat mult)))
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(if (> ed best-dmg)
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(checker (+ power 1) power ed)
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(checker (+ power 1) best-power best-dmg))))))
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(checker 0 0 0)))
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; iterate across a range of armor classes
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(define iter
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(let ((max-power 6)
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(attack 6)
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(dmg 5.5)
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(threat 20)
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(mult 3))
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(lambda (ac max-ac)
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(explicit-apply find-best-power max-power attack ac dmg threat mult)
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(if (> ac max-ac) #f (iter (+ ac 1) max-ac)))))
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(iter 10 30)
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