Re: [Chicken-users] matchable egg usage question

[Alan Post]

On Sat, Jan 29, 2011 at 11:23:54AM +0900, Alex Shinn wrote:
> So by deliberately limiting match we force people
> to write faster code.  At the same time, it's more
> verbose code - if you really want a match as powerful
> as prolog you could implement it and deal with the
> fact that it can be very slow in some cases.  And in
> that case you will eventually need to add a way to
> explicitly commit matches (i.e. "cut" in prolog) for
> decent performance.
> 
> [I'm not completely consistent in this, though,
> because the tree patterns I added do in fact
> require more complex searching and backtracking.
> But tree searches require this in general.]
> 

Alex, will you explain what I'd doing wrong here using
tree searching patterns?

(pretty-print (map
  (match-lambda
    (('foo *** '(bar 1)) #t)
    (_ #f))
  '((foo (bar 1))
    (foo (a (bar 1)))
    (foo (a (b (bar 1))))
    (foo (a (b (c (bar 1))))))))

Only the first form |(foo (bar 1))| is returning #t here.
The remaining forms return #f.  I would expect all of them
to return true, based on my naive understanding of the ***
operator.

-Alan
-- 
.i ko djuno fi le do sevzi