> The -> macro is a clever hack which allows you to "thread" values through expressions. It implicitly adds the value as the first argument to the first forms, the result of that form as the first argument for the next, etc. Because the core library is quite well-designed, this works 90% of the time. Then the other 10% you need ->> which does the same but adds the implicit argument at the end of the forms. And that's not always enough either, so they decided to add a generic version called as-> which binds the value to a name so you can put it at any place in the forms. These macros also don't compose well.

This is the biggest criticism of clojure I agree with the author on. Trying to compose threading macros is extremely annoying even though it’s not that difficult to refactor. Somewhere in the thread, you’ll want to put the return value of the previous function in a different argument place. I am not sure the reasoning behind designing the macros this way. With how well the language is designed, this annoyance has always seemed out of place and somewhat of an after thought. I made my own macro [0] as an experiment to circumvent this annoyance... which was an interesting experience (both writing and using the macro). Still, I don’t think it’s a good enough solution so I’m still trying to think of better ways to implement thread macros in clojure because I love the idea.

[0] https://github.com/cj-price/pipe.dream