On 17 July 2010 23:57, Laurent PETIT <laurent.pe...@gmail.com> wrote: > Hi, > > 2010/7/17 Paul Richards <paul.richa...@gmail.com> >> >> The "Programming Clojure" book states: "Functions that use dynamic >> bindings are not pure functions.." (P2.0, page 174). >> >> I do not understand why this must be the case, can someone explain why? > > Because then the result of the function does not *only* depend on its input > arguments. >
Hm, I'm still a little confused.. Are you saying that if a function make use of any value which is def'd from outside, then it is not pure functional? In this small example: (def forty-two 42) (defn func [] (* forty-two forty-two)) (defn other-func [] (binding [forty-two 6] (func))) In this example, which of these functions would be considered side effect free, and which would be considered pure functional? Is it the case that both are side effect free, but only "other-func" is pure? (This would seem to go against what the book says) According to the book "other-func" is impure (since it uses "binding" - aka dynamic bindings).. Yet in this example it seems more pure than "func". -- Paul Richards @pauldoo -- 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
