🚀 go-pugleaf

:: From: kers@hplb.hpl.hp.com (Chris Dollin) writes:
:: Message-ID: <KERS.92Nov12085629@cdollin.hpl.hp.com>
:: [...]  define 5 ++( x, y ); lvars x, y; x + y + 1 enddefine; [...]
: From: hrubin@pop.stat.purdue.edu (Herman Rubin)
: Message-ID: <BxMCxA.3nM@mentor.cc.purdue.edu>
: [...] I would accept that as the insertion of the ++ operator.

:: (Pop is an open-stack language), ``x * y'' means ``push x, push y,
:: call -'', and ``f(x)'' means ``push x, call f''.
: But I would object to any language which insists that we use a
: strictly stack machine.  Pushing, popping, and calling are to be
: avoided unless necessary.  Otherwise things just run too slowly to be
: of more than theoretical use.

This is yet another case of confusing the abstract notation with a
concrete implementation.  Just because the abstract semantics has the
model of a stack is NO reason to suppose that this forces one to
implement the model using an explicit stack with explicit push and pop
operations.  (Not being intimately familiar with Pop, it may be that
Pop *does* require an explicit stack in the implementation, but that
can't be told just from what Chris said.  Certainly he explicitly said
that the "call" operation may be open-coded in such a way as to
involve no actual call operation at runtime, as a property of the
operation, thus:)

:: *Some* procedure calls are coded in-line, but this is not a property of
:: being (syntactically) operators; it is a property of being a particular
:: procedure, such as fast_front, or fi_+.


( BTW, note the difference between a stack explicit in the notation, vs
  one explicit in the implementation.  This is the opposite of the case
  of pointers vs references previously discussed. )
--
Wayne Throop  ...!mcnc!dg-rtp!sheol!throopw