Re: [Chicken-users] amb egg bug/confusion
On Thu, Mar 15, 2012 at 01:38:19AM +0100, Thomas Chust wrote: On Wed, 2012-03-14 at 18:23 -0600, Alan Post wrote: [...] (pretty-print (let ((s (amb 0 1 2))) (amb-collect s))) [...] produces: [...] (0) [...] Hello, to me this behaviour looks correct. amb-collect is supposed to collect all the different values its argument can take on, but in your example s is not an ambivalent expression -- the fact that s is bound to a value produced by amb only makes the let expression ambivalent. To phrase it more technically: Every amb-collect creates a new dynamic scope for backtracking. Any ambivalence introduced in that dynamic scope will be resolved and the results will be collected but any outer dynamic scope will not be affected. Thomas, John, Thank you both very much. I did manage to start properly using the amb egg, and completed a one-off homework assignment: https://github.com/alanpost/permaculture-design-course/blob/master/guild/README amb is very neat. I'll likely throw larger datasets and more interesting constraints at it as I continue to explore this problem space. -Alan -- .i ma'a lo bradi cu penmi gi'e du ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] amb egg bug/confusion
On Mon, Mar 19, 2012 at 5:55 AM, Alan Post alanp...@sunflowerriver.orgwrote: On Thu, Mar 15, 2012 at 01:38:19AM +0100, Thomas Chust wrote: On Wed, 2012-03-14 at 18:23 -0600, Alan Post wrote: [...] (pretty-print (let ((s (amb 0 1 2))) (amb-collect s))) [...] produces: [...] (0) [...] Hello, to me this behaviour looks correct. amb-collect is supposed to collect all the different values its argument can take on, but in your example s is not an ambivalent expression -- the fact that s is bound to a value produced by amb only makes the let expression ambivalent. To phrase it more technically: Every amb-collect creates a new dynamic scope for backtracking. Any ambivalence introduced in that dynamic scope will be resolved and the results will be collected but any outer dynamic scope will not be affected. Thomas, John, Thank you both very much. I did manage to start properly using the amb egg, and completed a one-off homework assignment: https://github.com/alanpost/permaculture-design-course/blob/master/guild/README amb is very neat. I'll likely throw larger datasets and more interesting constraints at it as I continue to explore this problem space. Wow, another permaculturist on the chicken scheme list, what is the probability of that? I got my design certification just over a year ago. Nice work on the guild design! Do you have further plans for the code? -Alan -- .i ma'a lo bradi cu penmi gi'e du ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] amb egg bug/confusion
On Mon, Mar 19, 2012 at 09:18:29AM -0700, Matt Welland wrote: On Mon, Mar 19, 2012 at 5:55 AM, Alan Post [1]alanp...@sunflowerriver.org wrote: On Thu, Mar 15, 2012 at 01:38:19AM +0100, Thomas Chust wrote: On Wed, 2012-03-14 at 18:23 -0600, Alan Post wrote: [...] * (pretty-print (let ((s (amb 0 1 2))) (amb-collect s))) [...] produces: [...] * (0) [...] Hello, to me this behaviour looks correct. amb-collect is supposed to collect all the different values its argument can take on, but in your example s is not an ambivalent expression -- the fact that s is bound to a value produced by amb only makes the let expression ambivalent. To phrase it more technically: Every amb-collect creates a new dynamic scope for backtracking. Any ambivalence introduced in that dynamic scope will be resolved and the results will be collected but any outer dynamic scope will not be affected. Thomas, John, Thank you both very much. *I did manage to start properly using the amb egg, and completed a one-off homework assignment: [2]https://github.com/alanpost/permaculture-design-course/blob/master/guild/README amb is very neat. *I'll likely throw larger datasets and more interesting constraints at it as I continue to explore this problem space. Wow, another permaculturist on the chicken scheme list, what is the probability of that? I got my design certification just over a year ago. Nice work on the guild design! Do you have further plans for the code? * Ossum! I'm inclined to agree with Jorg and say it's because it's *Chicken* Scheme. _ I do have further plans for the code. I'm taking a 7-weekend course, with 2 weeknds left. I won't be working on it again until I finish the course, which happens at the end of April. I'm not sure in which direction I'll go first: it really depends on which problem in front of me I have the best data on. This project convinced me that I needed to start compiling and collecting such data: the constraint exploration was the finishing touch and my playground, and the more data I have the more options I have to play with. A local-to-me ecologist is interested in sitting down and brainstorming, I hope something interesting comes of that. -Alan -- .i ma'a lo bradi cu penmi gi'e du ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] amb egg bug/confusion
On Mon, Mar 19, 2012 at 10:05:19PM +0100, Jörg F. Wittenberger wrote: On Mar 19 2012, Alan Post wrote: On Mon, Mar 19, 2012 at 09:18:29AM -0700, Matt Welland wrote: On Mon, Mar 19, 2012 at 5:55 AM, Alan Post A local-to-me ecologist is interested in sitting down and brainstorming, I hope something interesting comes of that. -Alan Alan, now I you made me curious. Which of the ecologists is going to sit down? Will the result relate more to plants? Or is the egg system going to get a layer where one can bind those tentative identifiers used within the implementation of the importing module by specifying constraints instead of source locations upon import? I'd love it! The things I found myself wanting: + I wanted to know why some elements were excluded. What constraints were filtering which plants? Basically: why did my final group represent only a fraction of my available plants? I wanted reporting data that I could see and play with. + I wanted a constraint library. stuff like require one of a set to have a property with value foo. and require every element of this set to have the property value foo. But also ensure 4 out of 5 property values are present. I can see myself developing this library if I use amb more. + I wanted to compare runs when I had different constraints. I'm confused on what exactly I want to compare: mostly I think I want to store the output along with the set of constraints in a notebook so I can refer to previous explorations. Any work I do here is pretty likely to be specific to my problem domain (plants), but perhaps something general would emerge. You've probably never heard of the ecologist, he's pretty obscure (hehe, I think it's a student at my local uni, but I'm not sure, we haven't met in real life.) -Alan -- .i ma'a lo bradi cu penmi gi'e du ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
[Chicken-users] amb egg bug/confusion
I'm confused by the following behavior in the amb egg: (require-extension extras amb) (pretty-print (amb-collect (amb 0 1 2))) (pretty-print (let ((s (amb 0 1 2))) (amb-collect s))) (exit) produces: (0 1 2) (0) I would expect both forms to produce (0 1 2). What am I missing? I'm trying to do something more complicated than the above, but this was the test case I was able to produce. -Alan -- .i ma'a lo bradi cu penmi gi'e du ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] amb egg bug/confusion
On Wed, 2012-03-14 at 18:23 -0600, Alan Post wrote: [...] (pretty-print (let ((s (amb 0 1 2))) (amb-collect s))) [...] produces: [...] (0) [...] Hello, to me this behaviour looks correct. amb-collect is supposed to collect all the different values its argument can take on, but in your example s is not an ambivalent expression -- the fact that s is bound to a value produced by amb only makes the let expression ambivalent. To phrase it more technically: Every amb-collect creates a new dynamic scope for backtracking. Any ambivalence introduced in that dynamic scope will be resolved and the results will be collected but any outer dynamic scope will not be affected. Ciao, Thomas -- When C++ is your hammer, every problem looks like your thumb. ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] amb egg bug/confusion
Alan Post scripsit: (pretty-print (let ((s (amb 0 1 2))) (amb-collect s))) You're assuming that the result of amb is an amb object that you can bind to a variable, but that's not how amb works. It provides a non-linear flow of control in the evaluation of its arguments, but once it terminates, it returns the single value produced by the first non-failing argument, in this case 0. -- Go, and never darken my towels again! John Cowan --Rufus T. Firefly http://ccil.org/~cowan ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
