Re: Re: Assignment no, dynamic scoping si (was: Wishes

terje at in-progress dot com (Terje Norderhaug) wrote:

> >
> >It is obvious that any function with implicit parameters cannot be used as a
first
> >class object (e.g. passed as parameter to other functions, or returned as their
> >result). Such functions will be difficult to combine with other functions and
> >generally to reuse. 
> 
> I suspect you are mistaken. Using function with implicit parameters as a first 
> class objects  works fine in Common LISP, where implicit parameters will be 
> captured in a closure that has the same extent as the function object.

No, I'm not mistaken. Read the article at:

http://citeseer.nj.nec.com/cache/papers/cs/11502/http:zSzzSzwww.cse.ogi.eduzSz~mbszSzpubzSzimplicit.pdf/lewis00implicit.pdf

In section 6. at the end of the left column on page 10 the authors say:

"Implicit parameters provide the same functionality as dynamic scoping in Lisp,
except that implicitly parameterized functions are not first-class, and thus can't
be passed as arguments to functions... Thus, we would argue that implicit parameters
give you the best of dynamic scoping, while avoiding its worst pitfalls."

Cheers,
Dimitre Novatchev.

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