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From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Newsgroups: comp.lang.misc
Subject: Re: Re^4: Closures (was Re: class-sic.)
Message-ID: <4023@skye.ed.ac.uk>
Date: 28 Jan 91 19:45:55 GMT
References: <446@data.UUCP> <2400030@otter.hpl.hp.com>
Reply-To: jeff@aiai.UUCP (Jeff Dalton)
Organization: AIAI, University of Edinburgh, Scotland
Lines: 19

In article <2400030@otter.hpl.hp.com> sfk@otter.hpl.hp.com (Steve Knight) writes:
>Yes, partial application can be used to implement a full-closure mechanism.

And so can a variety of other mechanisms.

>It is fairly easy to transform (nested) procedures so that they have no
>free-variables EXCEPT for global-variables -- this is akin to lambda-lifting
>but works equally well in imperative languages.  This transformation assumes
>partial application works, of course.

It also assumes that assignment to a frozen formal works (persists
across calls) w/o some additional translformation.  It doesn't, at
least not in Pop-11 as it was in '84 or so.

>Having transformed a program into this form, all closure-forming
>operations are trivially tackled by partial application, 

And just imagine yourself transforming your program into this form
so that you can trivially tackle some problem.