\chapter{Preface} #%{{{  \slang is an interpreted language that was designed from the start  to be easily embedded into a program to provide it with a powerful  extension language.  Examples of programs that use \slang as an  extension language include the \jed text editor, the \slrn  newsreader, and \sldxe (unreleased), a numerical computation  program.  For this reason, \slang does not exist as a separate  application and many of the examples in this document are presented  in the context of one of the above applications.  \slang is also a programmer's library that permits a programmer to  develop sophisticated platform-independent software.  In addition to  providing the \slang extension language, the library provides  facilities for screen management, keymaps, low-level terminal I/O,  etc.  However, this document is concerned only with the extension  language and does not address these other features of the \slang  library.  For information about the other components of the library,  the reader is referred to the \slang-library-reference.\sect{A Brief History of \slang} #%{{{  I first began working on \slang sometime during the fall of 1992.  At that time I was writing a text editor (\jed), which I wanted to  endow with a macro language.  It occured to me that an  application-independent language that could be embedded into the  editor would prove more useful because I could envision embedding it  into other programs.  As a result, \slang was born.      \slang was originally a stack language that supported a  postscript-like syntax.  For that reason, I named it \slang, where  the \em{S} was supposed to emphasize its stack-based nature.  About  a year later, I began to work on a preparser that would allow one to  write using a more traditional infix syntax making it easier to use  for those unfamiliar with stack based languages.  Currently, the  syntax of the language resembles C, nevertheless some  postscript-like features still remain, e.g., the `\var{%}' character  is still used as a comment delimiter.#%}}}\sect{Acknowledgements} #%{{{   Since I first released \slang, I have received a lot feedback about   the library and the language from many people.  This has given me   the opportunity and pleasure to interact with several people to   make the library portable and easy to use.  In particular, I would   like to thank the following individuals:     Luchesar Ionkov \tt{<lionkov@sf.cit.bg>} for his comments and     criticisms of the syntax of the language.  He was the person who     made me realize that the low-level byte-code engine should be     totally type-independent.  He also improved the tokenizer and     preparser and impressed upon me that the language needed a     grammar.     Mark Olesen \tt{<olesen@weber.me.queensu.ca>} for his many patches to     various aspects of the library and his support on AIX. He also     contributed a lot to the pre-processing (\var{SLprep}) routines.     John Burnell \tt{<j.burnell@irl.cri.nz>} for the OS/2 port of the     video and keyboard routines.  He also made value suggestions     regarding the interpreter interface.     Darrel Hankerson \tt{<hankedr@mail.auburn.edu>} for cleaning up and     unifying some of the code and the makefiles.     Dominik Wujastyk \tt{<ucgadkw@ucl.ac.uk>} who was always willing to test     new releases of the library.     Michael Elkins \tt{<me@muddcs.cs.hmc.edu>} for his work on the curses     emulation.     Ulli Horlacher \tt{<framstag@belwue.de>} and Oezguer Kesim     \tt{<kesim@math.fu-berlin.de>} for the \slang newsgroup and mailing list.          Hunter Goatley, Andy Harper \tt{<Andy.Harper@kcl.ac.uk>}, and Martin     P.J. Zinser \tt{<zinser@decus.decus.de>} for their VMS support.          Dave Sims \tt{<sims@usa.acsys.com>} and Chin Huang     \tt{<cthuang@vex.net>} for Windows 95 and Windows NT support.          Lloyd Zusman \tt{<ljz@asfast.com>} and Rich Roth \tt{<rich@on-the-net.com>}     for creating and maintaining \tt{www.s-lang.org}.  I am also grateful to many other people who send in bug-reports and  bug-fixes, for without such community involvement, \slang would not  be as well-tested and stable as it is.  Finally, I would like to  thank my wife for her support and understanding while I spent long  weekend hours developing the library.#%}}}#%}}}