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The Pascal triangle implemented recursively by it's cell relation definition using lazy scala streams
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| import scala.collection.immutable.Stream | |
| //create the Pascal triangle using scala Streams | |
| object Pascal extends App { | |
| def plus(a:Int, b:Int) = a+b | |
| def map2(str:Stream[Int], f:(Int, Int) => Int):Stream[Int] = str match { //pattern matcher doesn't seem to work properly | |
| case Stream.Empty => str | |
| case _ #:: Stream.Empty => str | |
| case a #:: tail => f(a, tail.head) #:: map2(tail, f) | |
| } | |
| val pascal:Stream[Stream[Int]] = (1 #:: Stream.Empty) #:: pascal.map(prev => map2(0 #:: prev, plus)) | |
| def printX(a:Any) = print(a+" ") | |
| pascal take 10 foreach {x => x foreach {printX(_)}; println()} | |
| } |
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