[cc because of (*) below]
First things first - on April 1st, I answered John's WASHINGTON press
release with:
>Despite the licensing issues mentioned in the press release, there seems
>to be a type based competitor to the monad approach. Here is the brief
>program description:
>
> AnnoDomini is Hafnium's Year 2000 tool. AnnoDomini is developed for
> IBM OS/VS COBOL and runs under Windows NT and Windows 95. AnnoDomini
> is based on a novel polymorphic type theory, which we have developed
> specifically for solving Year 2000 problems.
>..
I don't think that confused anyone, so it seems that readers of the
Haskell mailing list are generally willing to believe that type systems
have practical applications, even for COBOL;-)
Perhaps most of you knew about AnnoDomini already, but for completeness,
here is the URL that I omitted from the original press release:
http://www.hafnium.com/
Incidentally, parts of AnnoDomini seem to be written in SML (*), which
leads to the second point of this message: I've heard of several
projects now using SML for symbolic processing, analyis or generation of
code in other languages, and I wonder how many projects are using
Haskell for similar kinds of tasks?
Given all the work on pretty printing and parsing in Haskell, this seems
to be an "obvious" application area that should be able to take up a
category of its own on the Haskell home page, perhaps even generate some
"real world" applications, but so far, the examples are interspersed
among other categories and partially hidden in other tools.
I've found hints about Haskell programs generating GIF, PDF, HTML, ASDL,
C, C++, Haskell, Tcl/Tk, and reading JPEG, IDL, .h-files, parser
specifications, ASDL, MIDI, Haskell, C++, LaTeX, which would make a
quite impressive list to start with. But at the moment, I have no idea
how complete or correct this list is (Isn't there some work on XML? What
else? Any Y2K applications?-). Being part of other projects, it is also
not clear which of the programs already mentioned on haskell.org are
application-specific and which are general and reusable.
In other words, I would be interested to hear where someone uses Haskell
for any kind of meta-programming over another language (in contrast to
function call interfaces to or from other languages or implementations
of other, domain-specific languages in Haskell - as far as it is
possible to draw a line here..). It's probably not sensible to try and
distinguish between data formats and (domain-specific) programming
languages as object languages.
Claus
(*) I've just noticed that Phil Wadler's
"Functional Programming in the Real World"
http://www.cs.bell-labs.com/~wadler/realworld/index.html
page lists another Y2K tool, written in TXL. Shouldn't AnnoDomini
be added to the list, too?
Being partially written in Standard ML (see the paper for the
invited POPL talk 1999), it seems to be a perfect example "of the
other kind" of real world use of functional programming: not
re-implementing existing applications in a functional language (the
COBOL applications are converted to COBOL, not to SML) but trying
new ideas in a domain where both time to market and correctness are
more important than ultimate speed. Also, only the heart of the
software is implemented in a functional language (making use of
parser and lexer generators), and interaction with other languages
and tools is important for the complete package.
