Please tell us what features you'd like in news.ycombinator

>>vegash+0i
You can now include code in comments:

 (def codetree (file)
   (trav + 1 (readall (infile file))))

Anything that appears after two newlines and a blank space is treated as code, till there's a line that doesn't begin with a space. This is like the markdown convention, but you don't have to use four spaces; one will do.

Incidentally, the code above tells me the number of nodes in the code tree of a file. Not just leaves, which would be

 (len (flat (readall (infile file))))

but interior nodes as well. To me this is the best measure of how long a program is. I used to go by lines of code

 (def codelines (file)
   (w/infile in file 
     (summing test
       (whilet line (readline in)
         (test (aand (find nonwhite line) (isnt it #\;)))))))

but I found this was encouraging me to do the wrong things.

(This kind of test matters because I'm constantly trying to make news.yc shorter as a way of pushing functionality down into Arc.)

Here's trav, btw:

 (def trav (f base tree)
   (if (atom tree)
       (base tree)
       (f (trav f base (car tree)) (trav f base (cdr tree)))))

It traverses a tree, doing something at every node. So e.g. CL copy-tree would be

 (def copy-tree (tree) (trav cons (fn (x) x) tree))

If you're wondering how the second argument to trav in codetree could be 1, it's because a constant when called as a function simply returns itself. This turns out to be quite handy.

>>pg+Dq8
Stupid questions alert. ____________________________

In On Lisp, you mentioned that implementing continuations with closures via transformation to CPS could be accomplished by writing a code walker, but that this would be a "serious undertaking" in Common Lisp.

This struck me at the time and ever since as painful, but understandable. Macros aren't first-class objects in CL, so the code you're walking through could be very complex due to macro-expansion, and I could be wrong, but I don't remember if the resulting code would necessarily contain clues that tell us what macro generated it, etc.

Could one assume (and it is definitely an assumption, or speculation, not a deduction from what you've given us here!) that it would be much simpler in Arc? Say, a page or so of code?

>>mr_luc+7s8
Hmmm. I guess I could also ask "What does readall do?" and go on speculating to myself, but the stuff above is what I really want to know. Once I've defined something (macro, function), what does it look like in Arc? Is its structure, either before or after macroexpansion, available to play cute little tricks with?

I'll stop asking questions now. I feel I'm reaching the limits even of assumption and might start getting silly. (For instance: "Could I write a function that let me select nodes within a loaded function using CSS Selector syntax?", but that's just silly so I won't ask it).

zlacker