The Common Lisp Cookbook. Adam Petersen - Software Development Pages. The following article and code has been updated as the book Lisp for the Web. You can get it for any price you want at Leanpub. by Adam Petersen, April 2008 With his essay Beating the Averages , Paul Graham told the story of how his web start-up Viaweb outperformed its competitors by using Lisp. Lisp? Did I parse that correctly? What to expect Starting from scratch, we'll develop a three-tier web application. Utilize powerful open source libraries for expressing dynamic HTML and JavaScript in Lisp, develop a small, embedded domain specific language tailored for my application, extend the typical development cycle by modifying code in a running system and execute code during compilation, and finally migrate from data structures in memory to persistent objects using a third party database.
I'll do this in a live system transparent to the users of the application. This article will not teach you Common Lisp (for that purpose I recommend Practical Common Lisp ). The Lisp story. Conditions system in cl. On 2009-01-15, Ulrich Neumerkel <ulr... @mips.complang.tuwien.ac.at> wrote:> When in unwind-protect both the protected-form and the> cleanup-form produce an error or just throw, Common Lisp> (e.g. GCL) gives preference to the cleanup-form and not You can hardly do that what GCL does is Common Lisp behavior.
> the protected-form. What do you mean by preference to the protected form? They don't execute concurrently. Firstly, let's discuss the error (or, generally, condition) case. Non-local exits may be performed by INVOKE-RESTART, GO, RETURN-FROM and THROW. > Is there some rationale behind this behaviour? It makes a lot of sense to abort the original control transfer if a cleanupform invokes another one! (tagbody (unwind-protect (go end-a) (print 1) (if condition (go end-b)) (print 2) (print 3)) end-a (print end-a) (go end) end-b (print end-b) (go end) end) Let's suppose that CONDITION is true. Let's consider two possible designs: Design 1: Design 2: (unless condition ... remaining cleanup forms) Beyond Exception Handling: Conditions and Restarts. Copyright © 2003-2005, Peter Seibel One of Lisp's great features is its condition system.
It serves a similar purpose to the exception handling systems in Java, Python, and C++ but is more flexible. In fact, its flexibility extends beyond error handling--conditions are more general than exceptions in that a condition can represent any occurrence during a program's execution that may be of interest to code at different levels on the call stack. For example, in the section "Other Uses for Conditions," you'll see that conditions can be used to emit warnings without disrupting execution of the code that emits the warning while allowing code higher on the call stack to control whether the warning message is printed. To start, I'll introduce some terminology: errors, as I'll use the term, are the consequences of Murphy's law.
So, what does it mean to handle an error? Because each function is a black box, function boundaries are an excellent place to deal with errors. The Lisp Way Conditions. Successful Lisp - Cover.