(defn hallo [title]
  (println "hello" title))
(hallo "Steve")
(hallo "world")
(type hallo)

(defn addone [x]
  (+ x 1))
(addone 2)
(+ 1 1)
(def n 10)
(println n)
(addone n)
(println *command-line-args*)
(def mylist [1 5 7 12 42 58])
(addone mylist)
(map addone mylist)
(first mylist)
(last mylist)
(rest mylist)
(conj mylist 5000)
(last (conj mylist 5000))
(count "world")

Running that with bb returns

----- Error --------------------------------------------------------------------
Type:     java.lang.ClassCastException
Message:  clojure.lang.PersistentVector cannot be cast to java.lang.Number
Location: /home/robbie/bonjour.clj:8:3

----- Context ------------------------------------------------------------------
 4: (hallo "world")
 5: (type hallo)
 6: 
 7: (defn addone [x]
 8:   (+ x 1))
      ^--- clojure.lang.PersistentVector cannot be cast to java.lang.Number
 9: (addone 2)
10: (+ 1 1)
11: (def n 10)
12: (println n)
13: (addone n)

----- Stack trace --------------------------------------------------------------

The error is really several lines down, where he tried to (addone mylist)

I get a similar error with clojure:

$ clj -M /tmp/dude.bb
hello Steve
hello world
10
nil
Execution error (ClassCastException) at user/addone ().
class clojure.lang.PersistentVector cannot be cast to class java.lang.Number (clojure.lang.PersistentVector is in unnamed module of loader 'app'; java.lang.Number is in module java.base of loader 'bootstrap')

Full report at:
/var/folders/j9/xmjlcym958b1fr0npsp9msvh0000gn/T/clojure-7696729073006534719.edn

hah ok interesting

Think I should open a bug report on that?

no?

there is a line with (addone mylist) where mylist is a vector

Right. I just thought it weird the error output was not pointing to that line.

it points to the function addone and gives you vector can not be cast to number. that is usually enough to get to the root cause

what is in the stacktrace?

Yeah, it's not a big deal. The stack trace points to the line number with the error. The context part just had me blinking at it for a minute.