We also need to consider the "dimension" of referentiality. I can see
three levels here. Given
@a.mung
the .mung could return
A) a modified @a (treat @a as mutable)
B) a new array (treat @a as immutable)
C) a remapped array whose elements refer back to @a's elements
Currently .rotate is defined as A, but I could easily switch it to B,
so you'd have to write
@a.=rotate;
to rotate in place. If we did that, then we could conceivably set
things up with more PDLish C semantics so that
@a .= mung # A semantics
@b = @a.mung # B semantics
@b := @a.mung # C semantics
This implies, however, that the copy semantics of = are sufficiently
clever to snapshot all the referenced values of @a before clobbering
@a in the case of either:
@a .= mung
@a = @a.mung
But list assignment really ought to be doing that in any case.
Maybe .push is really sugar for .=append, and unshift is really sugar
for .=prepend.
Larry
