[m-dev.] ./2

[Thomas Conway]

Hi

One of the unintended consequences of using . for qualification is that
you can't use it as a function name anymore.

Consider this case for parsing:

:- type tokens
	--->	tokens(
			curr :: int,
			max  :: int,
			text :: string
		).

:- func (char.tokens) = tokens.
:- mode ((out.out) = in) is semidet.

C.Toks = Toks0 :-
    Toks0^curr < Toks0^max,
    string__unsafe_index(Toks0^text, Toks0^curr, C),
    Toks = Toks0^curr := (Toks0^curr + 1).


skipWs -->
    ( [C], { char__is_whitespace(C) } ->
    	skipWs
    ;
    	[]
    ).

name -->
    [C], { char__is_alpha(C) }, ....

DCG expansion does exactly the right thing and inserts variables in all
the right places, and presto! you can use DCGs with complex parsing states
not just lists. (Credit for this technique to Andrew Bromage, not me - I
just think it's useful.)

-- 
 Thomas Conway              Unicode for terrorists: U+0001 300C
 <conway at cs.mu.oz.au>         "Tie his hands behind his back"
 Mercurian )O+  
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