spark-shell cannot parse Scala lines that start with dot / period

Question

Whenever I find some Scala / Spark code online, I want to directly paste it into spark-shell to try it out. (I am using spark-shell with Spark 1.6 on both CentOS and Mac OS.)

Generally, this approach works well, but I always have problems when lines start with a dot / period (indicating a continuing method call). If I move the dot to the previous line, it works.

Example: Here is some code I found online:

val paramMap = ParamMap(lr.maxIter -> 20)
  .put(lr.maxIter, 30) 
  .put(lr.regParam -> 0.1, lr.threshold -> 0.55)

So when I paste this directly into spark-shell, I see this error:

scala> val paramMap = ParamMap(lr.maxIter -> 20)
paramMap: org.apache.spark.ml.param.ParamMap = 
{
    logreg_d63b85553548-maxIter: 20
}

scala>   .put(lr.maxIter, 30) 
<console>:1: error: illegal start of definition
         .put(lr.maxIter, 30) 
         ^

scala>   .put(lr.regParam -> 0.1, lr.threshold -> 0.55)
<console>:1: error: illegal start of definition
         .put(lr.regParam -> 0.1, lr.threshold -> 0.55)
         ^

However, when I instead move the dot to the previous line, everything is ok.

scala> val paramMap = ParamMap(lr.maxIter -> 20).
     | put(lr.maxIter, 30).
     | put(lr.regParam -> 0.1, lr.threshold -> 0.55)
paramMap: org.apache.spark.ml.param.ParamMap = 
{
    logreg_d63b85553548-maxIter: 30,
    logreg_d63b85553548-regParam: 0.1,
    logreg_d63b85553548-threshold: 0.55
}

Is there a way to configure spark-shell so that it will accept lines that start with a dot (or equivalently, so that it will continue lines even if they don't end in a dot)?

Answer 1

There must be no leading whitespace.

scala> "3"
res0: String = 3

scala> .toInt
res1: Int = 3

scala> "3"
res2: String = 3

scala>   .toInt
<console>:1: error: illegal start of definition
  .toInt
  ^

PS: Maybe it should ignore whitespace when a dot is detected. A JIRA was added on that concern here.