Re: Operator overloading?

On Sat, 27 Jul 2024 15:35:55 +0000, Anton Ertl wrote:

minforth@gmx.net (minforth) writes:

[[: ;]] define closures, but unlike gforth's more flexible
flat closures, they capture simply all upvalues (here local a).

>
Gforth's flag closures can be considered lower-level (they come out of
implementation ideas in the Scheme community) and are easier to
implement, but emulating closures that capture outer locals is more
cumbersome.

In MF36 quotations already have read/write access to the locals of the
parent function. So closures became a simple by-product through
capturing
the parent's locals stack and injecting it at startup during closure
runtime. When the closure finishes, the captured stack is simply
updated.
I don't know if this would be good enough for a Lisp/Scheme programmer,
but it works for my needs. And look Ma, no garbage collection. :-)

One other aspect is that in Gforth's closures the
programmer decides whether closures are allocated in the dictionary,
on the locals stack, on the heap, or elsewhere.

In MF36 it is only the locals stack. AFAIU in other programming
languagues there are closures where the parent function can be seen as
constructor. IOW call the parent function twice and you get different
xts/addresses. From this perspective MF36 closures would perhaps only
qualify as 'half-closures'.

This raises the question of why you want to use closures for this
task.  Why not use one of the object-oriented Forth packages, some of
which support value-flavoured fields (Mini-OOF2 among them AFAIK).

MF36 VALUEs and LOCALs are already built with method VTs. TO et al
just call the method in the correct method slot. You don't need to
program type-specific TO +TO *TO. For example
4 XTBUFFER: _VZMETHODS  Z@ Z! Z+ Z*  \ methods table for complex values
: ZVALUE  \ ( r: r1 r2 <name> -- ) complex value
   _vzmethods _(value) f, f, ;
Similarly for xVALUEs of all other data types, including strings and
matrices.