>>106531244
(defmacro internal--thread-argument (first? &rest forms)
"Internal implementation for `thread-first' and `thread-last'.
When Argument FIRST? is non-nil argument is threaded first, else
last. FORMS are the expressions to be threaded."
(pcase forms
(`(,x (,f . ,args) . ,rest)
`(internal--thread-argument
,first? ,(if first? `(,f ,x ,@args) `(,f ,@args ,x)) ,@rest))
(`(,x ,f . ,rest) `(internal--thread-argument ,first? (,f ,x) ,@rest))
(_ (car forms))))
What the fuck is this doing? f and x are not declared anywhere