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Why is (string-match "lisp" major-mode) not working, while (string-equal "lisp-interaction-mode" major-mode) is working?

string-match results in debugger message: (wrong-type-argument stringp lisp-interaction-mode)

But help states:

(string-equal S1 S2)

(string-match REGEXP STRING &optional START)

(S1 and S2 is a placeholder for STRING, right?)

I already know that (string-match "lisp" (prin1-to-string major-mode)) can be used to get the expected result.

  • 2
    (string-match "lisp" (symbol-name major-mode)) would be more precise, depending on what you want (derived-mode-p 'emacs-lisp-mode) might make sense. – npostavs May 30 '17 at 14:17
  • In addition, if you only want to check whether a pattern matches a string, so you don't care what the matched part is, then consider using string-match-p instead of string-match. – Drew May 30 '17 at 15:33
2

string-match doesn't allow symbols but string-equal does.

(string-equal S1 S2)

Return t if two strings have identical contents. Case is significant, but text properties are ignored. Symbols are also allowed; their print names are used instead.

Note that result of evaluating major-mode is not a string.

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