Hi Doug,
> And I notice that some of the non-terminals there have arguments, for example:
Yes, I had already suspected so, because the clauses produced by 'dcg'
had only the self-generated arguments.
Currently, 'dcg' simply generates the lists of arguments. If we also
want to have user-defined arguments, then 'dcg' would need to append its
own arguments to the user's.
However, this is a problem of how we define the syntax of 'dcg'.
Currently, we have
(dcg sentence nounPhrase verbPhrase) # [A]
this expands to
(be sentence ("@In" "@Out")
(nounPhrase "@In" "@1")
(verbPhrase "@1" "@Out") )
Now, if we want additional arguments, I see two possibilities:
1. We _always_ supply a list of arguments, then we would need
to write
(dcg sentence () (nounPhrase) (verbPhrase)) # [B]
This is not the intended style, right?
2. We rewrite 'dcg' to inspect each term. As long as each element is
atomic (as in [A]), it behaves as it does now. If there are lists (as
in [B]), then it appends its self-generated arguments.
Then
(dcg foo (@A) mumble (bar @A))
would expand to
(be foo (@A "@In" "@Out")
(mumble "@In" "@1")
(bar @A "@1" "@Out") )
Would this make sense?
BTW, because I expected someting like that, I chose to implement all
self-generated arguments as transient symbols, so that they can't
conflict with user-supplied arguments. :)
Cheers,
- Alex
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