[mercury-users] A subtlety about DCG variable threading

[Ralph Becket]

> It was my understanding that the only terms in a clause which would
> not receive DCG threading were those that were escaped with { }.

That is correct: DCG expansion is purely syntactic.

> My guess is that the process/3's modes are not compatible with those
> of the head of the DCG (specifically, they are not di and uo) and that
> somehow Mercury selectively engages in the biblical act of Passover on
> them because of this, the bloody mark on the door in this case being
> incompatible modes.

No.  Can you tell us what sort of error message you're getting?  Seeing
the signature of process/5 might allow us to offer better help.
--------------------------------------------------------------------------
mercury-users mailing list
post:  mercury-users at cs.mu.oz.au
administrative address: owner-mercury-users at cs.mu.oz.au
unsubscribe: Address: mercury-users-request at cs.mu.oz.au Message: unsubscribe
subscribe:   Address: mercury-users-request at cs.mu.oz.au Message: subscribe
--------------------------------------------------------------------------