published on October 21st, 2011
Prompted by this question on Stackoverflow I thought a little bit about macros that generate functions. Here is what I came up with:
(defmacro make-placeholders [n]
`(map eval
'~(for [cntr (range 0 n)]
`(defn ~(symbol (str "_" cntr))
{:placeholder true} [& args] (nth args ~cntr)))))
This is macro generates functions _0 .. _n-1 that calls nth on the list
of the arguments following it, so (_2 1 2 3 4) returns 3. I have not
made up my mind if it is really a good idea to do this, but for now it's
a clever hack - maybe I'll use it until I discover why it's a bad
idea...