Re: Lack of formal syntax undermines Ada

Adam Beneschan a écrit :
> There was an early, pre-1983, version of Ada that had a rule that
> functions couldn't have side effects; this version also had "value-
> returning procedures" for those cases where you really needed
> something that could have side effects with the syntax of a function.
> (I think value-returning procedures were allowed to have what are now
> referred to as OUT and IN OUT parameters, but I'm not sure.)  Since I
> don't remember a rule that functions weren't allowed to call
> procedures, I don't know how they expected the side-effect rule to be
> enforced; maybe the authors figured they could just decree it to be so
> and stick implementors with the burden of figuring out how.
The actual statement was:
"Side effects, e.g. assignments to non-local variables, are not allowed 
within functions, whether directly, or indirectly through other 
subprogram calls".

Quite a weak statement, as far as implementation is concerned, actually.

> This was a long time ago, so of course my memory is hazy.  I haven't
> looked to see if this draft version of Ada exists somewhere on the
> Internet.
> 
I doubt it. At that time, paper was governing the world (I only have a 
paper copy of the Green reference manual).

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