Can not evaluate function

I am following a beginner elisp tutorial. What did I do wrong? (setq os "Gentoo") (defun fetchOS () (insert "os: " os)) (fetchOS) Debugger entered--Lisp error: (void-function fetchOS) (fetchOS) (progn (fetchOS)) elisp--eval-last-sexp(nil) eval-last-sexp(nil) funcall-interactively(eval-last-sexp nil) command-execute(eval-last-sexp record) execute-extended-command(nil "eval-last-sexp" nil) funcall-interactively(execute-extended-command nil "eval-last-sexp" nil) command-execute(execute-extended-command)

need to add `(interactive)` in your `defun` if you want to execute it by something like `M-x`

eval-last-sexp only evaluates, well, the last sexp. You have three s-expressions in your code, so you will need to call eval-last-sexp with the cursor behind each of them. There's also eval-buffer which will evaluate all expressions in the buffer.

This is true but from the stack trace it doesn’t look like this was the problem. The function was called using eval-last-sexp, not with M-x

Yeah, it's just my guess because I saw `funcall-interactively` in the trace.

eval-buffer fixed it, thank you very much!

Yeah good point. I just wanted to clarify since OP is a beginner. Functions need to be (interactive) in order to be called interactively (ie, using M-x). But an interactive function can then call any non-interactive function without issue. From the stack trace, it looks like “eval-last-sexp” was called interactively, and then that function tried to evaluate (fetchOS). As another comment pointed out, the issue is probably that the definition of fetchOS was never evaluated.