;; biased-coin.pamela
;; PAMELA example: probabilistic plant activity model

(defpclass biased-coin [weight]
  :meta {:doc "A biased coin with configurable weight"}
  :fields {worth {:initial 0.0}}
  :methods [(defpmethod heads
              {:doc "Heads side of coin"
               :probability weight}
              [])
            (defpmethod tails
              {:doc "Tails side of coin"
               :probability (- 1 weight)}
              [])])

(defpclass coin-toss []
  :meta {:doc "Toss a biased coin"}
  :fields {coin {:initial (biased-coin 0.3)}}
  :methods [(defpmethod toss
              {:doc "Toss the coin once"}
              []
              (choose
               (choice (tell (coin :heads)))
               (choice (tell (coin :tails)))))])