Thanks for your replies. It's all clear now.
And thanks for the book! :)
On 01/Sep/10 5:49 AM, Shriram Krishnamurthi wrote:
Sorry for the delay. In this case, Eric's interpretation is the one I
had in mind!
On Mon, Aug 30, 2010 at 9:40 AM, Eric Tanter<[email protected]> wrote:
Hi Ionut, Jay,
I don't understand the question this way -- rather, how to maintain laziness
without introducing an extra variant of CFAE-Value, ie. reusing the Closure
variant to implement expression closures.
Maybe Shriram can confirm which interpretation is correct ;)
-- Éric
On Aug 30, 2010, at 9:21 AM, Jay McCarthy wrote:
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
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--
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:
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_________________________________________________
For list-related administrative tasks:
http://lists.racket-lang.org/listinfo/users
_________________________________________________
For list-related administrative tasks:
http://lists.racket-lang.org/listinfo/users
--
Ionuț G. Stan | http://igstan.ro
_________________________________________________
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