Re: Out parameters in a function

[Darren New <dnew@san.rr.com>]

Kent Paul Dolan wrote:
> 
> "Darren New" <dnew@san.rr.com> wrote:
> 
> > > >        RESULT high, low
> > >  h, l := split.int16 (365)
> 
> > Note that in virtually all these languages, what this means is "return
> > an anonymous tuple from the function."  AFAIK, FORTH is the only
> > reasonably common language where you can *actually* return multiple
> > values from a function, rather than returning a single structured value.
> 
> Ummm.  APL, PL/PGSQL, CLAIRE, ML (and so OCaml, JoCaml), ...

APL returns one value, which might be an array. SQL returns one value
which might be a table. I don't know CLAIRE. ML (if I understand it
correctly) returns one value, which is a tuple or list or scalar. Python
returns a tuple of values, or an object with slots, or whatever.

FORTH, on the other hand, allows for the equivalent of
 being
   do some computations
   return the first value
   do more computations
   return the second value
   do more computations
   if some condition holds
      return a third value
 end

Altho the syntax of the other languages make it pretty much as
convenient and efficient to return a single tuple/array/whatever and
treat it as an entire list.

If you actually compare it with the difference in Ada between out
parameters and multiple return values, I think you'll see why FORTH is
different from (my understanding of) these other languages, where said
languages are strongly typed. I don't think occam would allow you to
declare a function that returns either a string, or two integers, or an
array of floats, depending on the arguments, yes?

-- 
Darren New 
San Diego, CA, USA (PST). Cryptokeys on demand.
   The 90/10 rule of toothpaste: the last 10% of 
         the tube lasts as long as the first 90%.