Re: How to assert DCG clauses?

On 08/30/2013 10:11 AM, Wouter Beek wrote:
> ?- X =.. [':-',a,b], assert(X), listing(a).

Carlo's suggestion is completely correct.  I'd like to add one
remark though.  I think I'm seeing more and more

	Term =.. [':-',a,b]

or similar constructs.  This is completely equivalent to the
much more readable

	Term = (a :- b).

Even when using =.., there is no need for the quotes
in ':-'.  :- is an atom.  If it was not, a :- b would not
be valid syntax either.  It is an atom because `symbol
characters' glue together just like lower case letters.
So, also \== or =======> are atoms, regardless of whether
or not they are (declared as) operators.

You need =.. iff

	- You do not know the functor name at compile time
   OR
	- You do not know the number of arguments at compile
	  time

In all other cases, you `create' the term by writing it.  I
suspect that the confusion comes from the idea that you want
to `create' a term and therefore you want some `action' to
take place?

	Cheers --- Jan