Arc Forum | That example specifically? It was nonsense. My point was that you could, say, ...

Arc Forum

2 points by fallintothis 5355 days ago | link | parent

That example specifically? It was nonsense. My point was that you could, say, map macros (anonymous or not). Those used to inline functions, for instance: you want to use a macro like a function, but it's a macro for efficiency. Currently, you have to wrap it in a function, which is kludgey.

Silly example:

  ; instead of

  (map complement list-of-fns)

  ; you have to do

  (map [complement _] list-of-fns)

Actual example (news.arc and the karma macro):

  (def leading-users ()
    (sort (compare > [karma _]) ; instead of (compare > karma)
          (users [and (> (karma _) leader-threshold*) (~admin _)])))

Again, macros being first-class intuitively works like functions being first-class. So, with first-class macros you could have expressions return macros.

Silly example:

  ((if (mem 'x stuff) pull push) 'y stuff)

Actual example (my trace library http://www.arclanguage.org/item?id=10372):

  (mac m ...)

  ((traced m) ...) ; traced is a higher-order function
                   ; since m is a macro, (traced m) returns a macro

More popularly, Bawden's paper (http://people.csail.mit.edu/alan/mtt/) demonstrates writing a module system with first-class macros in which the modules are also first-class.