Thank U very much, Our project is about "programming language principle". during the semester we have been programming a compiler for Jack language in racket, and now we need to make a presentation on Racket language that includes all information about the principle that we learned.
2014-07-21 5:31 GMT+03:00 Matthias Felleisen <matth...@ccs.neu.edu>: > > On Jul 20, 2014, at 9:25 PM, Jon Zeppieri wrote: > > > On Sun, Jul 20, 2014 at 6:27 PM, Matthias Felleisen > > <matth...@ccs.neu.edu> wrote: > >> > >> The phrase "call-by-value is a reduction strategy" has no meaning per > se but is a left over from the time when people hadn't figured out the > above (pre 1070). > >> > > > > I apologize for spreading this nonsense. Is it the phrase "reduction > > strategy" that's the problem? In the paper you cited, you refer to > > "evaluation strategies" and "binding strategies" and list > > call-by-value (eager) and call-by-name (delayed) as examples of the > > former. Is the problem with "reduction strategy" that it properly > > refers to rules for reducing redexes in a lambda calculus (and not > > parameter-passing in a programming language)? Or is it just nonsense > > tout court? > > > Yeap. Strategies exist in any LC. A strategy is simply a function > that picks the next redex to reduce. Strategies have uses BUT not > to describe parameter-passing mechanism. The latter are turned into > axioms directly. For example > > BY NAME: (function (x) body) any-argument = body with all (free) x > replaced by any-argument > BY VALUE: (function (x) body) value-argument = body with all (free) x > replaced by value-argument > > So you see there are two calculi and they each come with a different > axiom but the SAME strategies. > > ;; --- > > The idea is so much ingrained in programmer's mind due to some > basic text books that I can't blame anybody and I am certainly > not blaming you. > > I just don't like it that the idea is repeated 40+ years > after it was debunked in my neighborhood :-) > > -- Matthias > > >
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