Practical Common Lisp

own syntax for declaring the types of loop variables. The special operator LOCALLY, mentioned in Chapter 20, does nothing but create a scope in which you can make declarations.

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The FASL files produced by COMPILE-FILE are implementation dependent and may or may not be compatible between different versions of the same Common Lisp implementation. Thus, they're not a very good way to distribute Lisp code. The one time they can be handy is as a way of providing patches to be applied to an application running in a known version of a particular implementation. Applying the patch simply entails LOADing the FASL, and because a FASL can contain arbitrary code, it can be used to upgrade existing data as well as to provide new code definitions.

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ASDF was originally written by Daniel Barlow, one of the SBCL developers, and has been included as part of SBCL for a long time and also distributed as a stand-alone library. It has recently been adopted and included in other implementations such as OpenMCL and Allegro.

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On Windows, where there are no symbolic links, it works a little bit differently but roughly the same.

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Another tool, ASDF-INSTALL, builds on top of ASDF and MK:DEFSYSTEM, providing an easy way to automatically download and install libraries from the network. The best starting point for learning about ASDF- INSTALL is Edi Weitz's 'A tutorial for ASDF-INSTALL' (http:// www.weitz.de/asdf-install/).

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SLIME incorporates an Elisp library that allows you to automatically jump to the HyperSpec entry for any name defined in the standard. You can also download a complete copy of the HyperSpec to keep locally for offline browsing.

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Another classic reference is Common Lisp: The Language by Guy Steele (Digital Press, 1984 and 1990). The first edition, a.k.a. CLtL1, was the de facto standard for the language for a number of years. While waiting for the official ANSI standard to be finished, Guy Steele—who was on the ANSI committee— decided to release a second edition to bridge the gap between CLtL1 and the eventual standard. The second edition, now known as CLtL2, is essentially a snapshot of the work of the standardization committee taken at a particular moment in time near to, but not quite at, the end of the standardization process. Consequently, CLtL2 differs from the standard in ways that make it not a very good day-to-day reference. It is, however, a useful historical document, particularly because it includes documentation of some features that were dropped from the standard before it was finished as well as commentary that isn't part of the standard about why certain features are the way they are.