使用scala生成包含符号流的句子

Question

我想使用Stream生成多个句子。我现在可以生成1个句子。

def main(args: Array[String]): Unit = {
println((generateSentence take 1).mkString)
}

这是我到目前为止的结果

zIYow5ZJn92TjbcKbTvCf vaRNqZs80Fi4LcU7 8izJggPbjz9brbMtWmvo bGK

现在，如果我想取2个句子，流将继续写入第一个句子

现在我如何将该流中的多个句子生成数组(或列表(

我想过将类型更改为Stream[List[String]]，但我不知道如何以正确的方式添加生成的(它给了我Exception in thread "main" java.lang.StackOverflowError(

带流[List[String]]代码：

/**
* Generate one sentences between 2 and 25 words
* @return
*/
def generateSentence : Stream[List[String]] = {
def sentences : List[String] = {
sentences.::((generateWord take between(2, 25)).mkString) /* This line gave me the Exception StackOverflow */
}
Stream continually sentences
}

原始代码我写

/**
* Generate one word between 2 and 25 char
* @return
*/
def generateWord: Stream[String] = {
def word : String = {
(Random.alphanumeric take between(2, 25)).mkString.concat(" ")
}
Stream continually word
}
/**
* Generate one sentences between 2 and 25 words
* @return
*/
def generateSentence : Stream[String] = {
def sentences : String = {
(generateWord take between(2, 25)).mkString 
}
Stream continually sentences
}

/* This one is from the Random library, as it was introduced with 2.13 (so I just backported it into my 2.12)*/
def between(minInclusive: Int, maxExclusive: Int): Int = {
require(minInclusive < maxExclusive, "Invalid bounds")
val difference = maxExclusive - minInclusive
if (difference >= 0) {
Random.nextInt(difference) + minInclusive
} else {
/* The interval size here is greater than Int.MaxValue,
* so the loop will exit with a probability of at least 1/2.
*/
@tailrec
def loop(): Int = {
val n = Random.nextInt()
if (n >= minInclusive && n < maxExclusive) n
else loop()
}
loop()
}
}
}

Answer 1

技巧点：(

您的方法生成无限递归：

def sentences : List[String] = {
sentences.::((generateWord take between(2, 25)).mkString)
}

类似于：

def sentences : List[String] = {
val result = sentences()
result.::((generateWord take between(2, 25)).mkString)
}

这是方式，很明显，它称自己为无限。因此，为了解决您的问题，您可以使用toList

def sentences : List[String] = {
generateWord take between(2, 25) toList
}