I am studying *The Reasoned Schemer, 2nd ed.* and translating its source code into Clojure.
https://github.com/philoskim/reasoned-schemer-for-clojure In the middle of studying the problem #98 of Chapter 3, I encountered an unexpected result like this. https://github.com/philoskim/reasoned-schemer-for-clojure/blob/master/src/rs/ch3.clj#L498 in 3.100 the expected result is (fagioli e pasta). So I debugged the code like this by using my *debux (* https://github.com/philoskim/debux) library. The dbg macro here just prints its executed result without interrupting the code execution. (use 'debux.core) (defn memberrevo [x l] (conde [(dbg (emptyo l)) u#] [s# (fresh [d] (dbg (resto l d)) (dbg (memberrevo x d)))] [s# (dbg (eq-caro l x))])) (run* [x] (memberrevo x '(pasta e fagioli))) Suprisingly, the execution order of the printed result is not what I expected. dbg: (emptyo l) => | #function[clojure.core.logic/==/fn--15821] dbg: (eq-caro l x) => | #function[clojure.core.logic/firsto/fn--16147] dbg: (resto l d) => | #function[clojure.core.logic/resto/fn--16152] dbg: (memberrevo x d) => | #function[rs.ch3/memberrevo/fn--21091] dbg: (emptyo l) => | #function[clojure.core.logic/==/fn--15821] dbg: (eq-caro l x) => | #function[clojure.core.logic/firsto/fn--16147] dbg: (resto l d) => | #function[clojure.core.logic/resto/fn--16152] dbg: (memberrevo x d) => | #function[rs.ch3/memberrevo/fn--21091] dbg: (emptyo l) => | #function[clojure.core.logic/==/fn--15821] dbg: (eq-caro l x) => | #function[clojure.core.logic/firsto/fn--16147] dbg: (resto l d) => | #function[clojure.core.logic/resto/fn--16152] dbg: (memberrevo x d) => | #function[rs.ch3/memberrevo/fn--21091] dbg: (emptyo l) => | #function[clojure.core.logic/==/fn--15821] dbg: (eq-caro l x) => | #function[clojure.core.logic/firsto/fn--16147] dbg: (resto l d) => | #function[clojure.core.logic/resto/fn--16152] dbg: (memberrevo x d) => | #function[rs.ch3/memberrevo/fn--21091] What I expected was as follows. dbg: (emptyo l) => | #function[clojure.core.logic/==/fn--15821] dbg: (resto l d) => | #function[clojure.core.logic/resto/fn--16152] dbg: (memberrevo x d) => | #function[rs.ch3/memberrevo/fn--21091] dbg: (eq-caro l x) => | #function[clojure.core.logic/firsto/fn--16147] dbg: (emptyo l) => | #function[clojure.core.logic/==/fn--15821] dbg: (resto l d) => | #function[clojure.core.logic/resto/fn--16152] dbg: (memberrevo x d) => | #function[rs.ch3/memberrevo/fn--21091] dbg: (eq-caro l x) => | #function[clojure.core.logic/firsto/fn--16147] ...... Because the code [s# (fresh [d] (resto l d) (memberrevo x d))] precedes [s# (eq-caro l x)] I cannot understand the unexpected result at all. Could anyone explain to me why this happens? -- 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. For more options, visit https://groups.google.com/d/optout.
