Scalaメモ20100727

忘れっぽいからめもっとく

forについて

//foreachで以下のように書いた場合とほぼ同じ
scala> for( c <-"string" )
     |   println(c)
s
t
r
i
n
g


scala> "string".foreach(println)
s
t
r
i
n
g


scala> val stringq  = for( c <- "string"){ c }
stringq: Unit = ()

scala> val stringq = "string".foreach{c => c}
stringq: Unit = ()

//mapと
scala> for( i <- 1 to 10)
     |   yield i * i
res22: RandomAccessSeq.Projection[Int] = RangeM(1, 4, 9, 16, 25, 36, 49, 64, 81, 100)

scala> val numbers = for( i <- 1 to 10)
     |   yield i*i
numbers: RandomAccessSeq.Projection[Int] = RangeM(1, 4, 9, 16, 25, 36, 49, 64, 81, 100)


scala> (1 to 10).map{ i => i * i }
res23: RandomAccessSeq.Projection[Int] = RangeM(1, 4, 9, 16, 25, 36, 49, 64, 81, 100)

scala> val numbers = (1 to 10).map{ i => i * i }
numbers: RandomAccessSeq.Projection[Int] = RangeM(1, 4, 9, 16, 25, 36, 49, 64, 81, 100)