clojure

问题 I'm getting an " Invalid anti-forgery token " when I try using POST method in a Clojure Webapp project I created using Compojure template. I researched, and Ring middle ware creates CSRF (cross site request forms) tokens to authenticated requests coming from other sites (to use someone else's credentials who has already logged in and access pages not allowed to access). These tokens are default, and we need to use ring.middleware 's wrap-params around our WebApp. Couldn't get anywhere much.

问题 Let us say I have a X.clojurescript and a X.clojure namespace. Everything in X.clojurescript is Clojurescript code, everything in X.clojure is Clojure code. Unfortunately, I cannot define macros directly in Clojurescript, I have to define them in Clojure and then bring them into a Clojurescript namespace using (ns X.clojurescript.abc (:require-macros [X.clojure.def :as clj])) This is fine. However, what if the macro (defined in X.clojure) is going to need to reference something defined in a

问题 As a concrete example for my question, here's a snippet in Python (which should be readable to the broadest number of people and which has a JVM implementation anyway): def memo(f): cache = {} def g(*args): if args not in cache: cache[args] = f(*args) return cache[args] return g How do industrial-strength languages compile a definition like this, in order to realize static scope? What if we only have nested definition but no higher order function-value parameters or return values, à la Pascal

问题 As a concrete example for my question, here's a snippet in Python (which should be readable to the broadest number of people and which has a JVM implementation anyway): def memo(f): cache = {} def g(*args): if args not in cache: cache[args] = f(*args) return cache[args] return g How do industrial-strength languages compile a definition like this, in order to realize static scope? What if we only have nested definition but no higher order function-value parameters or return values, à la Pascal

问题 I'm trying to follow this java tutorial for neo4j testing, but in Clojure. I'm using Leiningen for my dependency management, but that tutorial uses maven. According to the tutorial, maven would take the following dependency XML: <dependencies> <dependency> <groupId>org.neo4j</groupId> <artifactId>neo4j-kernel</artifactId> <version>2.0.0</version> <type>test-jar</type> <scope>test</scope> </dependency> ... </dependencies> It also says: Observe that the test-jar is crucial. Without it you would

问题 I want to generate a fn totally at runtime (i.e. the name and the arg symbols are decided at runtime, not in code) What's the best way to achieve this ? For example how can I implement the following function ? (defn gen-fn [name arg-symbols body] ... ... which would be used like this: (gen-fn "my-func-name" (symbol "x") (symbol "y") (println "this is body. x=" x)) Note that function name, the args and the body are not coded but can be decided at runtime 回答1: (defn gen-fn [n as b] (let [n

问题 In clojure 1.2RC1, I wish to obtain a function based on its name as string and evaluate it. Function definition (ns my-ns) (defn mycar [x] (first x)) The following worked: ((ns-resolve *ns* (symbol "mycar")) '(3 4)) ((intern *ns* (symbol "mycar")) '(3 4)) ((eval (symbol "mycar")) '(3 4)) but they seem ugly. Is there a better way? If not, which of the above is the most idiomatic? 回答1: This worked for me without using eval: user> (defn mycar [x] (first x)) #'user/mycar user> ((resolve (symbol

问题 I have a sequence s and a list of indexes into this sequence indexes . How do I retain only the items given via the indexes? Simple example: (filter-by-index '(a b c d e f g) '(0 2 3 4)) ; => (a c d e) My usecase: (filter-by-index '(c c# d d# e f f# g g# a a# b) '(0 2 4 5 7 9 11)) ; => (c d e f g a b) 回答1: make a list of vectors containing the items combined with the indexes, (def with-indexes (map #(vector %1 %2 ) ['a 'b 'c 'd 'e 'f] (range))) #'clojure.core/with-indexes with-indexes ([a 0]

问题 I have a sequence s and a list of indexes into this sequence indexes . How do I retain only the items given via the indexes? Simple example: (filter-by-index '(a b c d e f g) '(0 2 3 4)) ; => (a c d e) My usecase: (filter-by-index '(c c# d d# e f f# g g# a a# b) '(0 2 4 5 7 9 11)) ; => (c d e f g a b) 回答1: make a list of vectors containing the items combined with the indexes, (def with-indexes (map #(vector %1 %2 ) ['a 'b 'c 'd 'e 'f] (range))) #'clojure.core/with-indexes with-indexes ([a 0]

问题 I have a sequence s and a list of indexes into this sequence indexes . How do I retain only the items given via the indexes? Simple example: (filter-by-index '(a b c d e f g) '(0 2 3 4)) ; => (a c d e) My usecase: (filter-by-index '(c c# d d# e f f# g g# a a# b) '(0 2 4 5 7 9 11)) ; => (c d e f g a b) 回答1: make a list of vectors containing the items combined with the indexes, (def with-indexes (map #(vector %1 %2 ) ['a 'b 'c 'd 'e 'f] (range))) #'clojure.core/with-indexes with-indexes ([a 0]