🚀 go-pugleaf

There have been a few requests regarding parsing recently so I thought
I'd bundle up a (incomplete) paper I wrote and make it available.  You
can get it by anonymous ftp as :-

  pub/haskell/library/bevan/parsing.tar.Z:anonymous@animal.cs.chalmers.se

Here is the README file that comes with it :-

The associated DVI file contains an _incomplete_ _draft_[1] of a paper
about a simple method for parsing LL(1) languages[2].  It discusses a
variation[3] of the LL(1) method using continuations to drive the parsing
process.  The paper describes the construction of a parser and lexer
for the toy language Asple.  Haskell is used as the implementation
language and use is made of Haskell's ability to declare infix
operators so that the programs look similar to ordinary BNF.
The complete code is available as either "asple.gs" (for Gofer) or
"asple.hs" (see details at the end).

Note there is no discussion of constructing an abstract syntax tree
(that is due in a later paper, when I've actually finished the current
one!), for information on how to do this, see the file "asple_cc.shar"
which contains a parser that builds an abstract syntax for Asple and
then checks the associated context conditions.  The code does contain
comments so it shouldn't be too hard to work out what is going on.

-------
[1] I intended to finish it back in August, but events have overtaken
    me.  I'm only making it available in its incomplete form since
    there have been a number of requests regarding writing (simple)
    parsers in functional languages.
[2] With judicious fiddling of the continuations, it should be possible
    to create a backtracking parser and so deal with a large class of
    grammars.
[3] Since writing most of the paper I found the same sort of method
    being used in an example file in the Edinburgh ML library.  The
    difference being that there "exceptions" are used instead of
    continuations.  

Obtaining source code
---------------------

The files mentioned previously are all available by anonymous ftp from
the Haskell library (as is this file) :-

  pub/haskell/library:anonymous@dcs.glasgow.ac.uk
  pub/haskell/library:anonymous@nebula.cs.yale.edu
  pub/haskell/library:anonymous@animal.cs.chalmers.se
  pub/haskell/library/bevan:anonymous@animal.cs.chalmers.se

or by mail server :-

  To: bevan@cs.man.ac.uk
  Subject: b-server-request
  send haskell/asple.gs

... etc. for other files.

If you have any problems obtaining files, comments on the paper or
code, ... etc., feel free to contact me :-

Stephen J. Bevan <bevan@cs.man.ac.uk> 19921101