for (int i = 0; i < doubleArray.length; i++) { doubleArray[i] = doubles.get(i); } // Option 2: Use enhanced for loop syntax (described below), along with // additional index variable. // Better performance but extraneous index value hanging around int index = 0; // Automatic ...
for-yield与for-loop不同。它只是flatMap、map和withFilter函数组合的语法糖。同样在scala中最好不要使...
但Scala社区对宏的理解显然和最初的设计理念有偏差。因为Scala本身是没有传统意义的循环的(for-loop),所 以很多时候循环必须利用while或者foreach。但是部分追求效率的Scala程序员们利用宏为Scala写了一个传统循环,叫做cfor,被收录 在Spire(non/spire · GitHub)数学计算库中。cfor的写法如下: importspire.syntax.c...
An alternate way to do this in Scala is to use value binding in the for-loop’s definition, which works the same but can help to minimize the size and complexity of the expression block. Bound values can be used for nested iterators, iterator guards, and other bound values. Syntax: Valu...
import spire.syntax.cfor._// print numbers 1 through 10cfor(0)(_ < 10, _ + 1) { i = println(i)} 而这玩意运行效率如何呢?文章中做了一次测评,将cfor和zip写的一个算法作比较——在公布结果之前,我想说的是,zip并不是一个高度优化的方法,所以本身就慢很多,cfor用了26.1毫秒运行,zip方法用了...
The original Preface for the Scala Cookbook Chapter 1 Chapter 1 is not online yet. Chapter 2 Chapter 2 is not online yet. Chapter 3 Recipe 3.1, How to loop over a collection with for and foreach (and how a for loop is translated) ...
The name and the parameters of a main function are terminated with the=operator. The operator is followed with a block of body code. In Scala 3, white space is a part of the syntax. It is used to delimit the body of a function. ...
可以使用三个级别的连续等级库 [ { "operation": "shift", "spec": { "*": { "*": "@(1,id).&", "title": "@(1,id).books.&s[]" } } }, { "operation": "shift", "spec": { "*": "" } }, { "operation": "cardinality", "spec": { "*": { "id": "ONE", "user"...
syntax error: need types for every arg. type R = Doubletype alias deff(x: R)vs deff(x: => R)call-by-valuevs call-by-name (lazy parameters) (x:R) => x*xanonymous function (1 to 5).map( _*2 ) (1 to 5).reduceLeft( _+_ )anonymous function: underscore is positionally matched...
）数学计算库中。cfor的写法如下：importspire.syntax.cfor._// print numbers 1 through 10cfor(0)...