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scalascala-ide

toString on a negative number doesn't compile in Scala Worksheet

If I create a Scala Worksheet in Eclipse as follows:

object negative {

  2.toString                                //> res0: String = 2

  (2).toString                              //> res1: String = 2

  // compile error
  (-2).toString
}

the final line causes a compile error:

';' expected but ')' found. illegal start of simple expression

However, the same three lines compile and run fine within a normal Scala source file.

Why does this not work in the worksheet?

This is using Eclipse 3.7.2, Scala IDE 3.0.0.v-2_10, Scala Worksheet 0.1.4.v-2_10

[Updated: this question originally used toBinaryString, but the problem occurs even with toString, so I have simplified it]

Solution

  • It is a bug. The code in the main object (the first one) of a worksheet is instrumented before being executed. In the 2 mentioned case, the result of the instrumentation is not valid Scala code.

    But it is only a problem if the code is at the top level in the main object. If the code is moved to a function or a different object in the same file, it works fine.