Capitalizing letters that follow colons using 'replace-regexp-in-string'

Question

I want to capitalize letters that follow colons. Here is the code:

(replace-regexp-in-string ": \w" 'upcase ": really")

The result I expected is : Really. Instead I get : really.

Similarly, this also doesn't work:

(replace-regexp-in-string ": [:alpha:]" 'upcase ": really")

But this works:

(replace-regexp-in-string ": r" 'upcase ": really")

And this, too:

(replace-regexp-in-string ": [:alpha:]" 'upcase ": alright")

My LANG environment variable is set to en_US.UTF-8.

Answer 1

You need to double the backslash in a Lisp string:

(replace-regexp-in-string ": \\w" #'upcase ": really")

See the Elisp manual, node Syntax for Strings.

And a char class has chars inside [], so put [:alpha:] inside [].

(replace-regexp-in-string ": [[:alpha:]]" #'upcase ": really")

See the Elisp manual, node Regexp Special.