How to make emacs properly indent if-then-else construct in elisp

Question

When I indent if-then-else construct in emacs lisp, the else block doesn't indent properly. What I get is:

(defun swank-clojure-decygwinify (path)
  "Convert path from CYGWIN UNIX style to Windows style"
  (if (swank-clojure-cygwin)
      (replace-regexp-in-string "\n" "" (shell-command-to-string (concat "cygpath -w " path)))
    (path)))

where else form is not indented at the same level as the then form. Is there an obvious way to fix this?

Answer 1

I don't have the relevant documentation handy, but this seems to do what you want:

(put 'if 'lisp-indent-function nil)

Also, you misused the word "properly"; by definition, however emacs indents is "proper" :)

Answer 2

That is the proper indentation. A quote from the manual:

The word "else" is not written in the Lisp code; the else-part of an `if' expression comes after the then-part. In the written Lisp, the else-part is usually written to start on a line of its own and is indented less than the then-part:

 (if TRUE-OR-FALSE-TEST
     ACTION-TO-CARRY-OUT-IF-THE-TEST-RETURNS-TRUE
   ACTION-TO-CARRY-OUT-IF-THE-TEST-RETURNS-FALSE)

For example, the following if' expression prints the message4 is not greater than 5!' when you evaluate it in the usual way:

 (if (> 4 5)                               ; if-part
     (message "4 falsely greater than 5!") ; then-part
   (message "4 is not greater than 5!"))   ; else-part

Note that the different levels of indentation make it easy to distinguish the then-part from the else-part. (GNU Emacs has several commands that automatically indent `if' expressions correctly. *Note GNU Emacs Helps You Type Lists: Typing Lists.)

This is a feature, not a bug :-)