Re: Scheme mistakes (was Re: nil)

[Alan Bawden <address@hidden>]

   From: "Joe Marshall" <jrm@ccs.neu.edu>
   Date: Thu, 14 Aug 2003 16:09:20 -0400

   From: "Alan Bawden" <Alan@lcs.mit.edu>
   > 
   > Consider evaluating:
   > 
   >   (throw (f x) 42)
   > 
   > Since you know that the expression `(f)' must yield a continuation, the
   > old continuation can be discarded (and perhaps reclaimed by the garbage
   > collector) -before- you call the function `f'.  

   (throw (call-with-current-continuation (lambda (c) ...)) 42)


What about it?  In this case `c' will be a continuation that expects
another continuation, which will in turn be passed `42'.  So:

   (throw (call-with-current-continuation (lambda (c) (throw c k))) 42)

is the same as:

   (throw k 42)