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dcbriccetti/gist:b70a7ff65541d79c467d

Last active August 29, 2015 14:16
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Can you rewrite this to produce “combinations” for any nonzero value of “numDice”? (This is mostly academic curiosity.)
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gistfile1.scala
val combinations: Seq[Seq[Int]] = numDice match {
case 1 => for (a <- 1 to numSides) yield Seq(a)
case 2 => for (a <- 1 to numSides; b <- 1 to numSides) yield Seq(a, b)
case 3 => for (a <- 1 to numSides; b <- 1 to numSides; c <- 1 to numSides) yield Seq(a, b, c)
}
@mtm
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mtm commented Mar 14, 2015

Can't help with Scala (been away too long), but here's a way to do it in Clojure:

(defmacro die-rolls [num-dice num-sides]
  (let [sides (vec (range 1 (inc num-sides)))
        die-names (vec (repeatedly num-dice gensym))
        die-bindings (vec (mapcat #(list % sides) die-names))]
    `(for ~die-bindings
       ~die-names)))

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