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72 lines
1.7 KiB
Plaintext
72 lines
1.7 KiB
Plaintext
// conditional
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if (check) happy else sad
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// conditional sugar
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if (check) happy // same as
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if (check) happy else ()
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// multiple conditions
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if (check) happy else if(secondCheck) lessHappy else ()
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// while loop
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while (x < 5) { println(x); x += 1}
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// do while loop.
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do { println(x); x += 1} while (x < 5)
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// break
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// slides: https://www.slideshare.net/Odersky/fosdem-2009-1013261/21
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import scala.util.control.Breaks._
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breakable {
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for (x <- xs) {
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if (Math.random < 0.1) break
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}
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}
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// for comprehension: filter/map
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for (x <- xs if x%2 == 0) yield x*10
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// same as
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xs.filter(_%2 == 0).map(_*10)
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// for comprehension: destructuring bind
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for ((x,y) <- xs zip ys) yield x*y
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// same as
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(xs zip ys) map { case (x,y) => x*y }
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// for comprehension: cross product
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for (x <- xs; y <- ys) yield x*y
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// same as
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xs flatMap {x => ys map {y => x*y}}
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// for comprehension: imperative-ish sprintf-style
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// http://docs.oracle.com/javase/6/docs/api/java/util/Formatter.html#syntax
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for (x <- xs; y <- ys) {
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println("%d/%d = %.1f".format(x, y, x/y.toFloat))
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}
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// for comprehension: iterate including the upper bound
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for (i <- 1 to 5) {
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println(i)
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}
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// for comprehension: iterate omitting the upper bound
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for (i <- 1 until 5) {
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println(i)
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}
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// recursion
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// can yield a "java.lang.StackOverflowError" with large lists
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// this is because each recursive call of the function is waiting for the evaluation of the next
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def sum(ints: List[Int]): Int = ints match {
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case Nil => 0
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case x :: tail => x + sum(tail)
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}
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// tail recursion
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// this type of recursion will not throw StackOverflowError
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// this is because each recursive call of the function is fully evaluated
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def sum(ints: List[Int], accum: Int): Int = ints match {
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case Nil => accum
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case x :: tail => sum(tail, accum + x)
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}
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