Clojure Core

Namespaces

clojure
- core
  - protocols
- data
- inspector
- java
  - browse
  - browse-ui
  - io
  - javadoc
  - shell
- main
- pprint
- reflect
- repl
- set
- stacktrace
- string
- template
- test
  - junit
  - tap
- walk
- xml
- zip

1.3.0 permalink

1.2.0
1.3.0

pop

For a list or queue, returns a new list/queue without the first
item, for a vector, returns a new vector without the last item. If
the collection is empty, throws an exception. Note - not the same
as next/butlast.

1 Example top

link | changes
```
user=> (peek [1 2 3])
3
user=> (pop [1 2 3])
[1 2]
user=> (peek '(1 2 3))
1
user=> (pop '(1 2 3))
(2 3)
```
user=> (peek [1 2 3]) 3 user=> (pop [1 2 3]) [1 2] user=> (peek '(1 2 3)) 1 user=> (pop '(1 2 3)) (2 3)

Source clojure/core.clj:1366 top

(defn pop
  "For a list or queue, returns a new list/queue without the first
  item, for a vector, returns a new vector without the last item. If
  the collection is empty, throws an exception.  Note - not the same
  as next/butlast."
  {:added "1.0"
   :static true}
  [coll] (. clojure.lang.RT (pop coll)))

Vars in clojure.core/pop:

Used in 0 other vars

Comments top

1 comment(s) for pop.

tomby42

link

Small reminder:

Do not work for arbitrary seq but just for persistent types implementing clojure.lang.IPersistentStack (like clojure.lang.Persistent*).

Example:

user> (pop (cons 1 '()))
; Evaluation aborted.

do not work because type is clojure.lang.Cons but

user> (pop (conj '() 1))
()

works because type is clojure.lang.PersistentList.

Small reminder:
Do not work for arbitrary seq but just for persistent types implementing clojure.lang.IPersistentStack (like clojure.lang.Persistent*).
Example:

user> (pop (cons 1 '()))
; Evaluation aborted.