Your members list needs to be filled with things that can be called as functions, since that's what that code snippet does, and booleans definitely cannot be called as functions. That's what the error means, there's a boolean in your list and it's trying to cast it to an IFn (a Clojure function interface) when it is called as (member).
Can you show the lists you construct? Are they full of functions that take no arguments? Do you want the lists to be able to contain booleans too? On Mon, Jul 19, 2021 at 2:57 PM Jack Park <jackp...@topicquests.org> wrote: > Cora > > (every? (fn [member] (member)) members) > works fine on [constantly true & false > but fails with > java.lang.Boolean cannot be cast to clojure.lang.IFn > on the lists I construct. > > In truth, I thought all the code was working, but that turned out ot be an > artifact of the test I designed. When I changed the test conditions, > evaluate_and failed. > > > On Sun, Jul 18, 2021 at 5:00 PM Cora Sutton <c...@sutton.me> wrote: > >> Hello again Jack, >> >> On Sun, Jul 18, 2021 at 6:21 PM Jack Park <jackp...@topicquests.org> >> wrote: >> >>> (every? eval members) does not appear to work on a list of functions >>> designed to evaluate to a boolean. >>> >> >> If members is a list of functions then you would do: >> >> (every? (fn [member] (member)) members) >> >> Showing it work here: >> >> (every? (fn [member] (member)) [(constantly true) (constantly true)]) >> ;; => true >> (every? (fn [member] (member)) [(constantly true) (constantly false)]) >> ;; => false >> >> >>> That code is used in a function evaluateAnd >>> >>> Two simple tests >>> (evaluateAnd [true true] --> true >>> (evaluateAnd [true false] --> nil (why not "false" as the every? >>> examples show?) >>> >> >> In Clojure things are either "truthy" or "falsey", and the only "false" >> values are false and nil so returning nil is usually fine. Everything else >> is "truthy". I wouldn't worry about it returning nil since other things >> were broken anyways. >> >> https://clojure.org/guides/learn/flow#_truth >> >> >>> The specific code for building the list of functions is this >>> >>> (def x (atom [])) >>> (let [result (list (ref SimpleTrue) (ref SimpleFalse))] >>> (println "BAL1" result ) >>> (reset! x result) >>> ) >>> (println "BAL2" @x ) >>> >>> (@x) <<<< returns the atom's value >>> >>> And the final println is this >>> >>> BAL2 (#object[clojure.lang.Ref 0x335b5620 {:status :ready, :val >>> #object[ie4clj.Tests$SimpleTrue 0x6eb2384f >>> ie4clj.Tests$SimpleTrue@6eb2384f]}] >>> #object[clojure.lang.Ref 0x3c9c0d96 {:status :ready, :val >>> #object[ie4clj.Tests$SimpleFalse 0x31dadd46 >>> ie4clj.Tests$SimpleFalse@31dadd46]}]) >>> >>> evaluateAnd never saw the result, with this error message >>> >>> clojure.lang.PersistentList cannot be cast to clojure.lang.IFn >>> >> >> Refs are the wrong thing to use here. In fact I'd stay away from atoms >> and refs unless you have multiple threads that need to mutate the same >> values. They're just confusing things now, I think. >> >> >>> >>> The test which fails is this >>> >>> (def result (evaluateAnd (buildAndList) )) <<< fails here >>> (println "bar" result) >>> (result) >>> >>> The googleverse seems to agree that there are extra parens around the >>> value. Google isn't giving me an obvious way to take that value outside of >>> its surrounding parens (bal2 above). >>> Still looking, and hoping that solves the problem. >>> Maybe there's a way to go back to buildAndList and not return the value >>> with parens. >>> >> >> I think a key thing to explain is that in Clojure generally you're not >> making new types of collections. There's this famous-ish saying that >> Clojure holds to pretty well: >> >> "It is better to have 100 functions operate on one data structure than 10 >> functions on 10 data structures." >> - Alan Perlis >> >> Most functions in the Clojure world operate on a handful of basic data >> types and structures. This makes it really easy to chain and combine >> functions to slice and dice data since you don't need to convert between >> types. >> >> I don't think I've ever made a special collection type in Clojure, it's >> not all that common. So I'd suggest that while you're at this point in your >> journey you try to stick to the built-in Clojure collection types and use >> the built-in functions to operate on them. >> >> To give you a little direction, instead of a Person object you could make >> a hashmap like {:first-name "Jack" :last-name "Park"} and pass that >> around. And then you can make a function that operates on that. >> >> (defn full-name >> [person] >> (str (get person :first-name) " " (get person :last-name))) >> >> And then you could expand that to maybe {:first-name "Jack" :last-name >> "Park" :people-talked-to-on-mailing-list ["Cora Sutton"]} and then >> operate on a collection of people like: >> >> (defn people-talked-to-on-mailing-list >> [person all-people] >> (let [people-to-find (set (get person >> :people-talked-to-on-mailing-list))] >> (filter (fn [p] >> (people-to-find (full-name p)) >> all-people)) >> >> (people-talked-to-on-mailing-list jack all-people) >> ;; => {:first-name "Cora" :last-name "Sutton" >> :people-talked-to-on-mailing-list ["Jack Park"]} >> >> >> >>> On Sun, Jul 18, 2021 at 11:23 AM Cora Sutton <c...@sutton.me> wrote: >>> >>>> Hi Jack! >>>> >>>> I could be wrong but I think this could just be: (every? eval members) >>>> >>>> I see a few things here that seem strange to me so I wanted to share a >>>> few points that might be helpful (or might not, let me know either way) for >>>> future code. >>>> >>>> * So typically you don't want to def or defn within another function >>>> call since that will define a new value at the top level. >>>> >>>> (defn foo [] >>>> (def bar 1) >>>> (println (inc bar)) >>>> >>>> (foo) >>>> ;; ^^ calling foo will define bar at the top level >>>> >>>> bar >>>> ;; => 1 >>>> ;; whoops, didn't mean to have that at the top level like that >>>> ;; imagine if two different threads called that in parallel ::grimace:: >>>> >>>> Instead, you usually want to use the let function: >>>> https://clojuredocs.org/clojure.core/let >>>> >>>> So in your code you might use this something like: >>>> >>>> (let [result (atom true)] >>>> ....) >>>> >>>> The error you're seeing is from the (defn result ...) in your code, >>>> you're missing the argument vector [] after result -- so it would look >>>> like (defn result [] (atom true)) -- but you really don't want to defn >>>> like that, I think. >>>> >>>> * To update an atom's value you don't want to assign like that, you >>>> want to use swap! https://clojuredocs.org/clojure.core/swap! >>>> >>>> (swap! f >>>> (fn [cur-val new-val] (and cur-val new-val)) >>>> (eval member)) >>>> >>>> * You probably don't want to use an atom here. Atoms are usually for >>>> data that you intend to have multiple threads accessing. In this case it's >>>> just a value that changes during a single thread's execution here. >>>> >>>> How else could you solve this if not for the very convenient every? >>>> function? There are a bunch of ways! Here are a few, with things written >>>> out pretty explicitly so they're more clear. >>>> >>>> loop/recur: >>>> >>>> (loop [result true >>>> remaining-members members] >>>> (let [member (first remaining-members) >>>> remaining-members (rest members) >>>> new-result (eval member)] >>>> (if new-result >>>> (recur true remaining-members) >>>> false))) >>>> >>>> reduce v1: >>>> >>>> (reduce (fn [result member] >>>> (and result >>>> (eval member))) >>>> true >>>> members) >>>> >>>> reduce v2.0, that will now stop iterating once one of the members evals >>>> to false: >>>> >>>> (reduce (fn [_ member] >>>> (or (eval member) >>>> (reduced false))) >>>> true >>>> members) >>>> >>>> My point with sharing these is that in clojure usually the best way to >>>> solve these problems is to pass new values to the next iteration while >>>> accumulating a result instead of changing a variable on each iteration. Or >>>> to use one of these sweet built-in functions. >>>> >>>> Does that make sense? >>>> >>>> * I thiiiiiiink you might not mean eval but I'm interested in what kind >>>> of problem you're solving! :) >>>> >>>> Hope that helps! >>>> Cora >>>> >>>> On Sun, Jul 18, 2021 at 12:41 PM Jack Park <jackp...@topicquests.org> >>>> wrote: >>>> >>>>> I have a class which treats a sequence as a conjunctive list of >>>>> objects which, when evaluated, return a boolean. It is an attempt to use >>>>> doseq to walk along that list, evaluating each entry, and anding that >>>>> result with boolean atom. It fails. A sketch of the code is this - taken >>>>> from the error message: >>>>> >>>>> inside (defn AndList... >>>>> >>>>> (reify >>>>> ie4clj.api.Inferrable >>>>> (defn evalMembers >>>>> [members] >>>>> (defn result (atom true)) >>>>> (doseq [x members] >>>>> (result = (and result (eval x)))) >>>>> (println (clojure.core/deref result)) >>>>> (result))) - *failed: vector? at: [:fn-tail :arity-1 :params] >>>>> spec: :clojure.core.specs.alpha/param-list* >>>>> >>>>> It could be that my Java background is clouding my use of clojure. Any >>>>> comments will be appreciated. >>>>> >>>>> Thanks >>>>> Jack >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Clojure" group. >>>>> To post to this group, send email to clojure@googlegroups.com >>>>> Note that posts from new members are moderated - please be patient >>>>> with your first post. >>>>> To unsubscribe from this group, send email to >>>>> clojure+unsubscr...@googlegroups.com >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/clojure?hl=en >>>>> --- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Clojure" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to clojure+unsubscr...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/clojure/f67cfcd0-8e1e-4780-bc00-f6993979e7afn%40googlegroups.com >>>>> <https://groups.google.com/d/msgid/clojure/f67cfcd0-8e1e-4780-bc00-f6993979e7afn%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Clojure" group. >>>> To post to this group, send email to clojure@googlegroups.com >>>> Note that posts from new members are moderated - please be patient with >>>> your first post. >>>> To unsubscribe from this group, send email to >>>> clojure+unsubscr...@googlegroups.com >>>> For more options, visit this group at >>>> http://groups.google.com/group/clojure?hl=en >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "Clojure" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to clojure+unsubscr...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/clojure/CAMZDCY3BWybiXzgoYaKK958z%2BWqTKf0o_5p9fq-huwutco9onw%40mail.gmail.com >>>> <https://groups.google.com/d/msgid/clojure/CAMZDCY3BWybiXzgoYaKK958z%2BWqTKf0o_5p9fq-huwutco9onw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Clojure" group. >>> To post to this group, send email to clojure@googlegroups.com >>> Note that posts from new members are moderated - please be patient with >>> your first post. >>> To unsubscribe from this group, send email to >>> clojure+unsubscr...@googlegroups.com >>> For more options, visit this group at >>> http://groups.google.com/group/clojure?hl=en >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "Clojure" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to clojure+unsubscr...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/clojure/CAH6s0fwv-rKrWnXji_r4scaX9_jtAi1CRUWGLLNRj7iZtme4UA%40mail.gmail.com >>> <https://groups.google.com/d/msgid/clojure/CAH6s0fwv-rKrWnXji_r4scaX9_jtAi1CRUWGLLNRj7iZtme4UA%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> On Sun, Jul 18, 2021 at 6:21 PM Jack Park <jackp...@topicquests.org> >> wrote: >> >>> (every? eval members) does not appear to work on a list of functions >>> designed to evaluate to a boolean. >>> >>> That code is used in a function evaluateAnd >>> >>> Two simple tests >>> (evaluateAnd [true true] --> true >>> (evaluateAnd [true false] --> nil (why not "false" as the every? >>> examples show?) >>> >>> The specific code for building the list of functions is this >>> >>> (def x (atom [])) >>> (let [result (list (ref SimpleTrue) (ref SimpleFalse))] >>> (println "BAL1" result ) >>> (reset! x result) >>> ) >>> (println "BAL2" @x ) >>> >>> (@x) <<<< returns the atom's value >>> >>> And the final println is this >>> >>> BAL2 (#object[clojure.lang.Ref 0x335b5620 {:status :ready, :val >>> #object[ie4clj.Tests$SimpleTrue 0x6eb2384f >>> ie4clj.Tests$SimpleTrue@6eb2384f]}] >>> #object[clojure.lang.Ref 0x3c9c0d96 {:status :ready, :val >>> #object[ie4clj.Tests$SimpleFalse 0x31dadd46 >>> ie4clj.Tests$SimpleFalse@31dadd46]}]) >>> >>> evaluateAnd never saw the result, with this error message >>> >>> clojure.lang.PersistentList cannot be cast to clojure.lang.IFn >>> >>> The test which fails is this >>> >>> (def result (evaluateAnd (buildAndList) )) <<< fails here >>> (println "bar" result) >>> (result) >>> >>> The googleverse seems to agree that there are extra parens around the >>> value. Google isn't giving me an obvious way to take that value outside of >>> its surrounding parens (bal2 above). >>> Still looking, and hoping that solves the problem. >>> Maybe there's a way to go back to buildAndList and not return the value >>> with parens. >>> >>> On Sun, Jul 18, 2021 at 11:23 AM Cora Sutton <c...@sutton.me> wrote: >>> >>>> Hi Jack! >>>> >>>> I could be wrong but I think this could just be: (every? eval members) >>>> >>>> I see a few things here that seem strange to me so I wanted to share a >>>> few points that might be helpful (or might not, let me know either way) for >>>> future code. >>>> >>>> * So typically you don't want to def or defn within another function >>>> call since that will define a new value at the top level. >>>> >>>> (defn foo [] >>>> (def bar 1) >>>> (println (inc bar)) >>>> >>>> (foo) >>>> ;; ^^ calling foo will define bar at the top level >>>> >>>> bar >>>> ;; => 1 >>>> ;; whoops, didn't mean to have that at the top level like that >>>> ;; imagine if two different threads called that in parallel ::grimace:: >>>> >>>> Instead, you usually want to use the let function: >>>> https://clojuredocs.org/clojure.core/let >>>> >>>> So in your code you might use this something like: >>>> >>>> (let [result (atom true)] >>>> ....) >>>> >>>> The error you're seeing is from the (defn result ...) in your code, >>>> you're missing the argument vector [] after result -- so it would look >>>> like (defn result [] (atom true)) -- but you really don't want to defn >>>> like that, I think. >>>> >>>> * To update an atom's value you don't want to assign like that, you >>>> want to use swap! https://clojuredocs.org/clojure.core/swap! >>>> >>>> (swap! f >>>> (fn [cur-val new-val] (and cur-val new-val)) >>>> (eval member)) >>>> >>>> * You probably don't want to use an atom here. Atoms are usually for >>>> data that you intend to have multiple threads accessing. In this case it's >>>> just a value that changes during a single thread's execution here. >>>> >>>> How else could you solve this if not for the very convenient every? >>>> function? There are a bunch of ways! Here are a few, with things written >>>> out pretty explicitly so they're more clear. >>>> >>>> loop/recur: >>>> >>>> (loop [result true >>>> remaining-members members] >>>> (let [member (first remaining-members) >>>> remaining-members (rest members) >>>> new-result (eval member)] >>>> (if new-result >>>> (recur true remaining-members) >>>> false))) >>>> >>>> reduce v1: >>>> >>>> (reduce (fn [result member] >>>> (and result >>>> (eval member))) >>>> true >>>> members) >>>> >>>> reduce v2.0, that will now stop iterating once one of the members evals >>>> to false: >>>> >>>> (reduce (fn [_ member] >>>> (or (eval member) >>>> (reduced false))) >>>> true >>>> members) >>>> >>>> My point with sharing these is that in clojure usually the best way to >>>> solve these problems is to pass new values to the next iteration while >>>> accumulating a result instead of changing a variable on each iteration. Or >>>> to use one of these sweet built-in functions. >>>> >>>> Does that make sense? >>>> >>>> * I thiiiiiiink you might not mean eval but I'm interested in what kind >>>> of problem you're solving! :) >>>> >>>> Hope that helps! >>>> Cora >>>> >>>> On Sun, Jul 18, 2021 at 12:41 PM Jack Park <jackp...@topicquests.org> >>>> wrote: >>>> >>>>> I have a class which treats a sequence as a conjunctive list of >>>>> objects which, when evaluated, return a boolean. It is an attempt to use >>>>> doseq to walk along that list, evaluating each entry, and anding that >>>>> result with boolean atom. It fails. A sketch of the code is this - taken >>>>> from the error message: >>>>> >>>>> inside (defn AndList... >>>>> >>>>> (reify >>>>> ie4clj.api.Inferrable >>>>> (defn evalMembers >>>>> [members] >>>>> (defn result (atom true)) >>>>> (doseq [x members] >>>>> (result = (and result (eval x)))) >>>>> (println (clojure.core/deref result)) >>>>> (result))) - *failed: vector? at: [:fn-tail :arity-1 :params] >>>>> spec: :clojure.core.specs.alpha/param-list* >>>>> >>>>> It could be that my Java background is clouding my use of clojure. Any >>>>> comments will be appreciated. >>>>> >>>>> Thanks >>>>> Jack >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Clojure" group. >>>>> To post to this group, send email to clojure@googlegroups.com >>>>> Note that posts from new members are moderated - please be patient >>>>> with your first post. >>>>> To unsubscribe from this group, send email to >>>>> clojure+unsubscr...@googlegroups.com >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/clojure?hl=en >>>>> --- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Clojure" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to clojure+unsubscr...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/clojure/f67cfcd0-8e1e-4780-bc00-f6993979e7afn%40googlegroups.com >>>>> <https://groups.google.com/d/msgid/clojure/f67cfcd0-8e1e-4780-bc00-f6993979e7afn%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Clojure" group. >>>> To post to this group, send email to clojure@googlegroups.com >>>> Note that posts from new members are moderated - please be patient with >>>> your first post. >>>> To unsubscribe from this group, send email to >>>> clojure+unsubscr...@googlegroups.com >>>> For more options, visit this group at >>>> http://groups.google.com/group/clojure?hl=en >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "Clojure" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to clojure+unsubscr...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/clojure/CAMZDCY3BWybiXzgoYaKK958z%2BWqTKf0o_5p9fq-huwutco9onw%40mail.gmail.com >>>> <https://groups.google.com/d/msgid/clojure/CAMZDCY3BWybiXzgoYaKK958z%2BWqTKf0o_5p9fq-huwutco9onw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Clojure" group. >>> To post to this group, send email to clojure@googlegroups.com >>> Note that posts from new members are moderated - please be patient with >>> your first post. >>> To unsubscribe from this group, send email to >>> clojure+unsubscr...@googlegroups.com >>> For more options, visit this group at >>> http://groups.google.com/group/clojure?hl=en >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "Clojure" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to clojure+unsubscr...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/clojure/CAH6s0fwv-rKrWnXji_r4scaX9_jtAi1CRUWGLLNRj7iZtme4UA%40mail.gmail.com >>> <https://groups.google.com/d/msgid/clojure/CAH6s0fwv-rKrWnXji_r4scaX9_jtAi1CRUWGLLNRj7iZtme4UA%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clojure@googlegroups.com >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+unsubscr...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/clojure/CAMZDCY1wvo_N32dKV1g-9cZAmTbZUO5bRAXDGkdHm-7_VD_-Rg%40mail.gmail.com >> <https://groups.google.com/d/msgid/clojure/CAMZDCY1wvo_N32dKV1g-9cZAmTbZUO5bRAXDGkdHm-7_VD_-Rg%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/clojure/CAH6s0fyc%2BctV%2B1OgzWRYLsWevL97ouVkS1FGf0uGFtTcznRjUg%40mail.gmail.com > <https://groups.google.com/d/msgid/clojure/CAH6s0fyc%2BctV%2B1OgzWRYLsWevL97ouVkS1FGf0uGFtTcznRjUg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/clojure/CAMZDCY0qvUUrTmQtfcUocwWbr50juXzoZt%3DSmPr%3D0o%3DgRXoM2A%40mail.gmail.com.
