I have two lists:
(def xxa ["olp" "xyz"])
(def xxb ["ulove" "alove" "holp" "sholp"])
and a function trying to get the elements of the 1st list that are parts of elements of the 2nd list:
(defn in-array
[array1 array2]
(for [s1 array1 :when (some #(.contains %1 s1) array2)] s1))
(in-array xxa xxb) should return ["olp"]
but I get:
IllegalArgumentException Key must be integer clojure.lang.APersistentVector.invoke
I don't understand what that means. Can someone gives me some light?
Here's an attempt to make the discussion above into a clear answer for those who come along later. If I've missed something please let me know or edit:
Starting with the original example:
user> (def xxa ["olp" "xyz"])
#'user/xxa
user> (def xxb ["ulove" "alove" "holp" "sholp"])
#'user/xxb
user> (defn in-array [array1 array2]
(for [s1 array1 :when (some #(.contains %1 s1) array2)] s1))
#'user/in-array
And then as peter points out, an extra set of () would cause this error:
user> (in-array (xxa xxb))
IllegalArgumentException Key must be integer clojure.lang.APersistentVector.invoke (APersistentVector.java:284)
Which contains more code than is required to show the situation, so we can trim it down to:
user> (xxa xxb)
IllegalArgumentException Key must be integer clojure.lang.APersistentVector.invoke (APersistentVector.java:284)
which is a minimal case to show the problem. If we change this example to pass the expected type we can see that vectors, when called as a function, take a number and look that number up in themselves.
user> (xxa 1)
"xyz"
So finally we can correct the call and get the expected output, almost exactly:
user> (in-array xxa xxb)
("olp")
The result is a (lazy) sequence from the for expression and user3166747 had asked for a vector (non lazy, and random access) which we can get by adding a call to vec:
user> (defn in-array [array1 array2]
(vec (for [s1 array1 :when (some #(.contains %1 s1) array2)] s1)))
#'user/in-array
user> (in-array xxa xxb)
["olp"]
and now it matches exactly.
("olp")- the error alomst certainly means (if you are also runnig in a REPL) that some other definition is causing the error.in-arrayincorrectly. Try removing the parentheses around them like so:(in-array xxa xxb)(in-array xxa xxb)and in your comment(in-array (xxa xxb)).(in-array (xxa xxb)), Clojure is attempting to callxxaas function - which it can, arrays are functions of their indices, but those indices must be integers (hence the error), whichxxbis not - try(xxa 1)to see that in action.