Re: Narrowing vs. rewriting

From: Michael Hanus <hanus_at_I2.Informatik.RWTH-Aachen.DE>
Date: Thu, 3 Jul 1997 18:29:43 +0200

John Lloyd wrote:
> However, put yourself in the position of having to explain the computational
> model of Escher or Curry to an (inexperienced, say) programmer...
> In fact, this is just the Haskell story except Escher allows variables
> in expressions. Having taught Haskell to our big first class here, I feel
> very confident that I can explain this story and pretty soon have students
> writing conventional Haskell programs as well as LP-like ones.

In fact, I already did it in a course on declarative programming.
I started with Haskell and extended the lazy rewrite model to
allow the necessary instantiation of free variables which leads
naturally to logic programming. For this course, I used, as
you can imagine, Curry. A description of this experiment and
the course will appear in the proceedings of the PLILP'97.
You can find the paper also at

> This I have discussed earlier. But note one additional point. It isn't
> always disastrous for a computation to not compute far enough (i.e flounder).
> Whatever happens the first and last expressions are equal.

But isn't it disastrous to loop instead of computing a value?

Best regards,

Received on Do Jul 03 1997 - 19:34:00 CEST

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