Log of changes on this site
August 2001 through July 2002

Please refer to ChangeLog.html for the most recent changes

July 4, 2002

• Portable case-sensitive symbols, and the meaning of identifiers
• Portable implementation and validation of a and-let* special form (SRFI-2). The form is now a part of my standard Scheme prelude.

June 7, 2002

• An unbelievably simple algorithm for intersection testing of two segments of a circle or georectangles, with the correctness proof.
• Macro quotify: Another example of the systematical construction of R5RS macros

May 5, 2002

• Systematic Macro programming
• Two pitfalls in programming nested R5RS macros
• Syntax-rule-level ??!lambda and ??!apply
• Lambda-calculator as a R5RS macro

April 5, 2002

• SXML as a normalized database. An example of a complex SXML->XML translation that involves denormalizations, "table joins" and third-order tags.
• Monte Carlo Monad: arithmetics of "probabilistic numbers". How to write ordinarily-looking arithmetic expressions with variables denoting random values rather than numbers.

March 1, 2002

• New edition of the SXML specification. Besides stylistic changes and updates caused by the new version of the XML Infoset, the new edition introduces a @@ node for extensibility and specifies the SXML grammar in a more precise (and also in a more abstract, see SXML.scm) way. We also introduce a non-terminal namespace-id, and rename user-ns-prefix into user-ns-shortcut. We explain how the latter differs from XML namespace prefixes.
• An article `Similarity between instruction scheduling and imperative functional programming' is related to Andrew W. Appel's paper on Single Static Assignment.
• An article demonstrating that Scheme/CL macro-expansion models the non-strict computation of Haskell functions.

February 1, 2002

• Added a reference to a PADL02 presentation "A better XML parser through functional programming," which describes the derivation of the SSAX API.
• Added more References and Footnotes on Subtyping, Subclassing, and Trouble with OOP.

January 4, 2002

• Monadic Programming in Scheme
• How to read the whole file or a port into a string
  Several new pieces of sample code that illustrate the input parsing library

December 7, 2001

• Comparing SSAX and Expat XML parsers in features and performance
• Native implementations of the exception-handling SRFI (SRFI-12)
• A link to an on-line version of an article Speaking HTTP: A File-Uploader Tool, USENIX ;login: -- vol. 25, No. 2 -- April 2000, pp. 6-14.
• The XML and Scheme page is now written in SXML. Added references to the SSAX/SXML mailing list and to a lax parser of (perhaps invalid) HTML.

November 4, 2001

• SXML specification is presented better. The specification is written in SXML itself, which is later transformed to HTML, LaTeX and PostScript. It is available in all these formats.
• Version 4.9 of the SSAX XML parser. The new version is smarter about insignificant white space. A benchmark comparing SSAX and Expat in performance is also included.
• An assert macro with informative reports on failure
• A serially-numbering monad

October 5, 2001

• Provably perfect shuffling and its pure functional implementations
• Similarity between instruction scheduling and imperative functional programming
• Number-parameterized types and static computations in Haskell
• Categorical products in Haskell
• How to implement AND without pattern-matching

September 7, 2001

• Version 4.8 of the SSAX XML parser. The new version is roughly 10% faster than the previous one, and allocates half as much memory. It is easier to port; it works on more Scheme systems.
• ssax.sourceforge.net SSAX/SXML is also a project at SourceForge. SourceForge graciously provides mailing lists, forums, bug and feature request tracking systems. The SSAX CVS repository at SourceForge includes several sample SSAX applications and usable examples.
• The description of input stream parsing library is converted to SXML. The master file is parsing.scm. Added two pieces of sample code: to remove HTML/XML tags and comments from an input stream, and to count the number of occurrences of a string pattern in a file.

August 5, 2001

• Object-Oriented programming is a harmful methodology: a paper and especially a talk presented at Monterey 2001 workshop. Behavioral inheritance, one of the planks of OOP, is most troublesome. Behavior overriding is responsible for breaking separation between an interface and implementation. Behavior overriding inflates statement's context, which makes it difficult for a programmer to keep all the context in his short-term memory. As the paper shows, thinking that everything is an object (with its own reactive behavior) may lead to suboptimal solutions.
• The Input parsing module, other Scheme utilities documented on this site, and the Functional XML parsing framework now work on MIT Scheme, Release 7.5.2. The only change is the addition of a MIT-specific version of the standard prelude.
• Stream tokenizers now rely on a dedicated function for initial buffer allocation. The default policy is reusing a statically allocated buffer. This policy is optimal for Scheme systems without preemptive multi-threading and without shared substrings. The policy dramatically reduces the amount of garbage produced during, for example, parsing of large XML files.
• Higher-level i/o procedures -- write-substring, port-copy -- with a highly efficient fast path code.

August 2000 through July 2001

December 1995 through August 1996