On Jun 28, 2009, at 6:20 AM, Günter Kniesel wrote:
> 17 ?- assert(a,b).
> false.
>
> 18 ?- listing(a).
> :- dynamic user:a/0.
>
> user:a.
>
> true.
For what it's worth, I tried this in two other Prolog
systems and got the same result.
What really puzzles me is why the students came up with
this misconception in the first place. I mean, they'd have
seen examples of assert/1, but not examples of assert/2.
PLT Scheme has an interesting approach. They've divided
the language into levels, and the initial teaching level
doesn't have very much. You have to explicitly move to
a richer level. If you are an expert coming to PLT Scheme
for the first time, expecting everything you know to be there,
it's a nuisance, but it sounds like a good way to protect
beginners from (some) accidents.
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