Hi Ionut, In this section PLAI is asking you to write more of a meta-interpreter where you use the thunks of the language you are writing the interpreter in.
Jay On Mon, Aug 30, 2010 at 2:23 AM, Ionut G. Stan <[email protected]> wrote: > Hi, > > I'm pretty sure this is not the best mailing list to ask about PLAI, but as > I've found no other I decided to try here (I've found about PLAI on the > original DrScheme mailing list, and racket-lang.org seems to mention PLAI in > the "Learning" section). I won't mind if I don't get an answer to my > question though. Maybe there's a dedicated mailing list? > > So, here's my problem, just in case :) > > I'm stuck understanding what a certain exercise is asking me. I'm talking > about exercise 8.2.1 from chapter 8, Implementing Laziness. > > The exercise asks to implement laziness without using expression closures, > but using thunks instead. Thunks being just like closure, except they don't > have arguments bound to them. What I don't understand is the fact that this > is the way I've implemented expression closures. They're just like closures, > except for the argument part. So, from my point of view, is just a matter of > renaming my algebraic data types. > > I'm using Haskell to implement all the languages discussed in the book, and > my ADT for CFAE/L-Value looks like this: > > data CFAELValue > = NumberValue Int > | Closure String CFAEL Environment > | Expression CFAEL Environment > deriving (Eq, Show) > > So, Expression is the constructor for expression closures, and the only > difference when compared to Closure is the String argument. > > Is anyone willing to shed some light on what the exercise does actually > require me to do? > > Just for completeness, I've put the Haskell sources for all the languages up > to chapter 8 on Github: http://github.com/igstan/plai-haskell. CFAE-L.hs is > the one used for chapter 8. > > Thanks. > > -- > Ionuț G. Stan | http://igstan.ro > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users -- Jay McCarthy <[email protected]> Assistant Professor / Brigham Young University http://teammccarthy.org/jay "The glory of God is Intelligence" - D&C 93 _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
