[mercury-users] Circular lists

[Richard A. O'Keefe]

	I guess we could emit a warning every time you return a string from C
	code, or pass or return a complex type from C code,

Why are these things dangerous?  In Quintus Prolog, passing strings in either
direction was guaranteed safe, thanks to copying.  In ESH, a very nice Scheme
system from Sun, passing C data structures to Scheme and back again works
perfectly safely.

	but to do anything
	more would require impossible analysis of the C code itself (and
	separate compilation only makes the problems worse).

You apparently envisage checking arbitrary code;
I envisage checking _checkable_ code.  If the code is for some reason
impossible to analyse, that is in itself a danger sign.