[m-dev.] diff: io__call_system/4

[Andrew Bromage]

G'day.

You (Fergus Henderson) wrote:

> I think that is a poor interface.
> We shouldn't encode values in integers like that.

> I think it would be better to just return error(_)
> for cases where the invoked process was killed with a signal.

I disagree completely.  This is useful information which a program should
be allowed to act on sensibly.

I agree, BTW, that the "final" version should throw an exception in this
case.

Perhaps a better interface for now is to return a type such as:

:- type io__system_result(T)
	--->	ok(T)
	;	signal(int)
	;	error(io__error).

Cheers,
Andrew Bromage