<div>On 11/6/07, Matthias Felleisen <<a href="mailto:matthias@ccs.neu.edu">matthias@ccs.neu.edu</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> On Nov 6, 2007, at 9:26 AM, Joel J. Adamson wrote: > >> The closure is a data representation that is just a struct with two >> fields: >> >>  -- one field that points to the environment of the function >> definition >>  -- another field that points to the code of the function definition > > How concrete are we talkin' here?  Are you saying the MzScheme > interpreter builds a struct Yes. > in the sense that I could manipulate it > with struct functions (if I knew what it was called)? You do have two operations in your language (Scheme) on closures:   [1] construction aka lambda (the true syntax of function defs)   [2] application (that is, function application) Your language does not give you access to the fields of the struct otherwise. > Are we starting to get at the "What's so great about Lisp?" here? It's the same for all rationally constructed interpreters, VMs, and compilers.</blockquote><div> Sorry to butt in, but seeing that Joel is a biostatistician, I should mention that R has closures.  (Rationally constructed is not the first adjective that springs to mind when I think of R). They have the canonical account implementation in the scoping demo, and you can find other examples in the code. </div>  <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> >> Time to read HtDP and PLAI now. -- Matthias > > I read the first chapter of PLAI last night, and I'm really enjoying > it.  I skimmed through much of HtDP, and found plenty of good > conceptual angles in it.  Perhaps I'll go back and read some of the > later chapters.  And you'll be happy to know I'm reading through the > Little Schemer for the second time. All of these are good books. HtDP is TLS/TLL for people who like words. Or I finally figured out how to respond to Dan :-) > Thanks for all your help --- this list is fantastic, You're welcome. _________________________________________________   For list-related administrative tasks:   <a href="http://list.cs.brown.edu/mailman/listinfo/plt-scheme"> http://list.cs.brown.edu/mailman/listinfo/plt-scheme</a> </blockquote></div>