scala fun

(from scala-user)

Can someone tell me whether this "gotcha" is type-unsafe or am I just not realizing something? This bit me in production code today (via java interop).

scala> def x: java.math.BigDecimal = null
x: java.math.BigDecimal

scala> def y = Option[BigDecimal](x) orElse Option[BigDecimal](x)
y: Option[BigDecimal]

scala> for (z <- y) println(z)
java.lang.NullPointerException

Year 2020:

...
java.lang.IllegalArgumentException: null value for BigDecimal
  at scala.math.BigDecimal.(BigDecimal.scala:406)
  at scala.math.BigDecimal$.apply(BigDecimal.scala:335)
  at scala.math.BigDecimal$.apply(BigDecimal.scala:332)
  at scala.math.BigDecimal$.javaBigDecimal2bigDecimal(BigDecimal.scala:347)
  at .y(:12)
  ... 28 elided

Kmett talking...

zipper ("hello", "world")
  % down _1
  % fromWithin traverse
  % focus .~ 'J'
  % rightmost
  % focus .~ 'y'
  % rezip
("Jelly", "world")