Explicit topic variable _ disappears in a module's outermost scope

[catb0t]

module X {
  [1, 2].each{
    say ( _ )      # unbound 
    { _ }          # unbound
  }
}

[INFO] `_` is parsed as a prefix method-call at no_topic.sm line 2
sidef: Okie dokie, I'm dead

File : no_topic.sm
Line : 2 : 8
Error: variable <_> is not declared in the current scope

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  say ( _ )
        ^
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Am I doing something wrong? The code works if you use |block_scope| binding in the each and the sub-block, it's only _ alone that isn't bound.

[catb0t]

Thanks for the fix! And sorry for the unending barrage of bug reports, I do try to see if I can fix them myself first, but you know the code best.

[trizen]

Thanks for the bug-reports. I admire your testing skills. No reason to be sorry. :)

[catb0t]

With the simplifications I think you have introduced a regression, _ is unbound in the following, even inside a function or method (I can't remember if this was always the case)

var f = true
while (f) {
  assert(_)
  f = false
}

[trizen]

This is intended: the if and while parameter must be explicitly defined, otherwise it would pollute the scope with a topic variable (_), most of the time unnecessarily.

var f = true
while (f) { |_|
  assert(_)
  f = false
}

This also allows the following code to work as intended (using _ from map inside if):

[1,2,3,4,5].map { if (_.is_even) { _/2 } else { 3*_ + 1 } }

[catb0t]

Aha, right.