[m-dev.] Fw: Replacement syntax for DCGs

[Ralph Becket]

Peter Ross, Monday, 26 November 2001:
> 
> These are some of the points that you need to consider.

Michael Day addressed most of these in his reply, but here's my take.

> How to you declare the predicate/function which uses this threading?

Just as with DCGs, the _ ! _ notation is purely syntactic sugar for
the definition.

> What about it you want it to have multiple modes?

Again, as with DCGs, the mode declarations are entirely separate from
the _ ! _ notation.

> What about it you want to using this syntax on higher order.  What are
> the implications of that?

Michael's suggestion was what I had in mind, using the same thing as is
currently done for DCGs.  For example,

	array ! io ! list__foldl2(
		( array ! io ! pred(X::in, di, uo, di, uo) is det :-
			...
		),
		[1, 2, 3]
	)

> I would be nice to generalise this to the case of having more than one
> pair of state arguments threaded.  How would you declare that?

See above!

- Ralph
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