🚀 go-pugleaf

> I realised a while back that you can use DCGs for many programs that
> don't look like parsing.  My favorite (and most grotesque) is flatten:
> 
> flatten(List, FlattenedList):-
>         phrase(flatten(List), FlattenedList).
> 
> flatten([]) --> [].
> 
> flatten([Head|Rest]) -->
>         flatten(Head),
>         flatten(Rest).
> 
> flatten(List) -->
>         [List].

I cannot see what is so *grotesque* in trying to give a condensed
expression of the regularities a computation contains.  

I suppose you disapprove of using DCG for something which seems the
opposite of syntactic analysis.  However, especially in Prolog, one
should be used with non-directional thinking.

Olivier Ridoux