Common Lisp Programmatic Keyword

Question

Is there a function in Common Lisp that takes a string as an argument and returns a keyword?

Example: (keyword "foo") -> :foo

Answer 1

Here's a make-keyword function which packages up keyword creation process (interning of a name into the KEYWORD package). :-)

(defun make-keyword (name) (values (intern name "KEYWORD")))

Answer 2

The answers given while being roughly correct do not produce a correct solution to the question's example.

Consider:

CL-USER(4): (intern "foo" :keyword)

:|foo|
NIL
CL-USER(5): (eq * :foo)

NIL

Usually you want to apply STRING-UPCASE to the string before interning it, thus:

(defun make-keyword (name) (values (intern (string-upcase name) "KEYWORD")))

Answer 3

There is a make-keyword function in the Alexandria library, although it does preserve case so to get exactly what you want you'll have to upcase the string first.

Answer 4

In this example it also deals with strings with spaces (replacing them by dots):

(defun make-keyword (name) (values (intern (substitute #\. #\space (string-upcase name)) :keyword)))

Answer 5

In case, you can change the string to start with colon sign :

use read-from-string directly.

Here is another version of make-keyword:

(defun make-keyword (name)
           (read-from-string (concatenate 'string ":" name)))

Answer 6

(intern "foo" "KEYWORD") -> :foo

See the Strings section of the Common Lisp Cookbook for other string/symbol conversions and a detailed discussion of symbols and packages.