World: r3wp

You can't do such construction in Red/System.

Right, that's what I mean

Assignments can't be used inside an expression, nor can functions 
that don't have a return value.

Btw, allowed expressions are now documented: http://static.red-lang.org/red-system-specs.html#section-5.1

Any plans to support this?

Red/System is not meant to be a REBOL replacement, you will need 
to wait for Red.

But isn't that the point? :-) There are no replacements for REBOL 
at all, and we can't wait any longer

Red/System cannot be a REBOL replacement, it doesn't live at the 
same level of abstraction.

I know, but this one is very doable. I guess it would be a nice project 
for Brian

I could remove the compiler check, so that your code "might" compile, 
but that opens a hole for several others issues.

That compiler check has been added to solve the issues reported here: 
https://github.com/dockimbel/Red/issues/93

assignements don't return a value in Red ? 
It should be doable without pain.

Currently, no.

There is a possible evolution documented in the specification for 
that, allowing also multi-assignments as a side-effect.

a cool side effect

Yeah :-)

It sort of pulls the base out from under my efforts to wrap all external 
functions to return logic!

You could just write wrapper functions.

I did, but after that, I was expecting to plug them into ANY and 
ALL :-)

or use logic! as return value in the imported function definition?

(as return type)

No, we discussed that

I don't remember the conclusion?

Only possible when the #import returns 0 and 1 exactly

Ah right!

Anyway, returning 0 for succes is unnatural for humans, but very 
natural for C. If there is no REBOL like way to process the reverse 
logic! return, the C way becomes more attractive, and the code shifts 
towards C instead of REBOL

I still don't get why you can't solve that with wrapper functions?

How do you mean? Writing three extra functions just for that one 
ALL expression?

I mean writing wrappers for low-level ZMQ imported functions, so 
that they return consistent values. For example, RECEIVE should return 
a message! or null, but not a 0 that needs to be casted to logic!.

I did. NULL also needs to be cast to logic

Also, those wrappers could handle the low-level ZMQ errors, so that 
the user don't have to do it.

No, because there is no standard for error reporting, like in REBOL. 
You have to do error trapping the C way

I just mean findind a way to catch those 0 values transparently.

There is no 0, only NULL, and this is my attempt at implementing 
the error catching, transparent or not

I know you don't want more changes before implementing Red, and that's 
fair enough, but this is something we'll need eventually

Here a code example of how you could solve that:
	msg: receive ....
  	if zmq-error? [...process error...]


zmq-error? could just check a flag set by last zmq low-level calls.

Such constructs would make the binding a lot more high level and 
would require a lot more code. I'm trying to keep complexity down 
for simplicity and performance

calls => call

The added code won't make any significant overhead in performances 
for a network communication library, the slow parts are the network 
exchanges.

What bothers me most is the added complexity that doesn't really 
solve the problem. Error handling is often something that needs to 
be done locally, because that's where the knowledge is to handle 
the problem most gracefully

We don't have goto and longjumps, either, so there's little leeway 
for implementing a transparent error trapping framework

Btw, your code snippet could be rewritten as:

message: receive socket 0
unless all [
	as-logic message
	end-message message
	;wait 1
	send socket  as [byte-ptr!] reply  1 + length? text  0
][

 prin "Received request: "  print as-c-string message-data message
	print zmq-form-error system-error
]

Huh, I guess I have been too aggressive with the prin "..." line 
:)

If you want the function to return a logic! status and a result to 
be able to handle it locally, the result needs to fetched through 
a pointer, which also raises complexity. We can't handle addresses 
very well yet, either, because get-words only work for native functions

My point was: don't return a logic! statut from functions like RECEIVE, 
rather set a flag and check it after RECEIVE call.

statut => status

RECEIVE doesn't return logic?

That rewrite doesn't work. It mixes up successful and unsuccessful 
receiving

Yeah right, I was confused by your will to return a logic!.

I'm flexible. :-) Not everything returns logic, only the cases that 
can