How to make a global function without `require`?

In .emacs.d I have the following ``` core/lib.el modules/abc/xyz.el init.el early-init.el ``` I have `foo` and others defined in `lib.el` and want these functions to be available in all `modules` without using `(require 'lib)`

You need to [autoload them](https://www.gnu.org/software/emacs/manual/html_node/elisp/Autoload.html). But really, it's poor form to depend on anything without declaring it. Not just in elisp.

Thank you for your suggestion. I'm moving away from Doom Emacs. It has some built-in functions and macros such as very useful `map!`, `after!` macros... which just worked without declaring them. I want to do the same thing with my config

You need to load that file lib.el before all other modules.. the mechanism for doing that is.... (require) The function itself lives in a global namespace. So the require is just about telling emacs which file to load in a way that doesn't require you to hard code path names all over. It's line #include <stdlib.h> in C - where exactly is stdlib.h located? Well another mechanism tells the compiler -- in elisp, that's the variable 'load-path'. &#x200B; You could always just be sure to do (load-file "<path to lib.el>") early in your init.el and then you'd have all those functions available, but it is fairly brittle - if anything changes in init.el then all of a sudden your 'foo' function doesn't exist anymore and then ??? confusing! Good elisp modules shouldn't magically fail because a global fn that is loaded for them stopped being loaded for them. &#x200B; In short: why not require?

Many thanks for your clarification. I didn't know function is global by default. That's interesting. In short, I need `load-path` to make sure `lib` and `modules` files are available, then make sure that using `(require 'lib)` before `(require 'xyz)`. By doing so, all functions in `lib.el` are available in `xyz.el`, am I correct?

@ieure your solution is great but it's not how I want to achieve. @codemuncher gave me a better explanation.