Hi, I got an exception using eval and I do not understand why! Can anybody explain what happens?
Here is a small piece of code showing the problem: (defn eval-phi [avec phi] (eval `(let ~avec ~phi))) ; The idea of eval-phi is the evaluation of ; arbitrary lists where the symbols are ; defined in avec ; example: ; in avec the symbol p is defined as true ; and the symbol foo as a function adding 2 (def avec ['p true 'foo (fn [x] (+ 2 x))]) ; here are two lists (def phi '(and p (= 7 (foo 5)))) (def psi '(and (not p) (= 7 (foo 5)))) ; and here their evaluation (eval-phi avec phi) ; => true (eval-phi avec psi) ; => false ; second approach: ; the attempt to give the definition of a ; function in avec by a function which ; returns a function leads to an exception: (defn make-adder [n] (fn [x] (+ n x))) ((make-adder 2) 5) ; => 7 ; here the second definition of a binding vector: (def avec' ['p true 'foo (make-adder 2)]) (eval-phi avec' phi) ; CompilerException java.lang.ExceptionInInitializerError ; in my mental model of the substitution of symbols by ; their value there should be no difference between the ; first approach and the second. ; Actually avec' contains the function returned by make-adder ((nth avec' 3) 5) ; => 7 ; Why does avec' leads to an exception? *Kind regards,* *Burkhardt Renz* -- 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.
