[adwf]

I think the problem is when you get into more complicated nesting of code than a simple function. For instance:

(setf new-links (append new-links (link-scanner (cu-body url-hash) (parse-uri cu-url url-hash)))))

That's a quick one-liner I wrote for part of a webcrawler. In Lisp you don't need to know anything much about parsing that syntax except that after an open parenthesis, you're going to have a function/macro followed by parameters.

Going by your example I could either do:

setf new-links (append new-links (link-scanner (cu-body url-hash) (parse-uri cu-url url-hash))))

or

  setf new-links 
    append new-links
      link-scanner 
        cu-body url-hash 
        parse-uri cu-url url-hash

or

  setf new-links append
    new-links link-scanner
      cu-body url-hash
      parse-uri cu-url url-hash

In the first example I've hardly improved anything, just removed a single pair of parens.

In the second example, I've split each new nested function call onto a new line and indented. This leaves "raw" parameters on the same line as the function call, whilst moving function params to the next line. (Note that Lisps don't make any distinction between the two usually).

In the third example, I've gone for some unholy mix where I've left the first nested function call on the same line as the first "raw" params, but moved the next params to the next line and repeated with any following functions. This is a mess...

Personally I think the 2nd example is actually quite readable. But here's the catch; this was 1 line from a 60 line function. If every line was multiplied by 5, is a 300 line function still as readable? And that's before you even get into any considerations of how to implement macros and other potentially complicated constructs.

EDIT: Admittedly, not every line is going to grow by a factor of 5, but it'll still be enough to turn a one page function into a multi-page function.