Re: "dict"ionary typing?

On Dec 5, 2013 8:15 PM, "Richard A. O'Keefe" <[email protected]> wrote:
>
> On 5/12/2013, at 11:01 PM, Michael Hendricks wrote:
>
> >  One
> > might reasonably use append/3 as a function in three different modes.  I
> > haven't implemented it yet, but I'm considering a new feature for
> > library(func) inspired by Ciao's notation.  Specifically, a single ~
marks
> > the argument to be used as output for *this* call.
> >
> >  ?- writeln(append([a,b],[c,d],~)).
>
> It's just too bad that ~ is a perfectly good data term
> as it stands and append([a,b],[c,d],~) is also a perfectly
> good data term as it stands, so this query is perfectly
> meaningful right now, meaning something else.  This is a
> recipe for confusion.

I agree that the ambiguity will lead to some confusion.  Thinking of func
users, I estimate that the probable benefit minus the probable confusion
still leaves us with a large net gain in utility.  These estimates are
highly subjective and probably influenced by my own "ambiguity tolerance",
so the future may prove me wrong.

On a tangent, this comment somehow reminded me of some interesting research
in natural language:  Ambiguity can lead to greater communication
efficiency by relying on information already present in the context:
http://web.mit.edu/newsoffice/2012/ambiguity-in-language-0119.html

Their research reminds me of the confusion I faced when I first saw
append/3 or witnessed type inference in ML or learned about typeclasses in
Haskell.

> Oh yes, there is a >> logical << approach to functions in
> Prolog called "narrowing".  There's been quite a lot written
> about it.

Thank you for the reference. That's an area I haven't read about before.

-- 
Michael
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