link-grammar parser

It looks like the best way to do it right now is to

cd ~/Projects
mkdir link-grammar
cd ./link-grammar
wget http://www.abisource.com/downloads/link-grammar/5.0.8/link-grammar-5.0.8.tar.gz
tar -zxf ./link-grammar-5.0.8.tar.gz
cd ./link-grammar-5.0.8
./configure
make
sudo make install

This should build and install the link-grammar parser (most importantly, it will put the link-grammar.so on the $PATH, so that we can easily link against it, when compiling Lisp bindings.

The clinkgrammar.lisp found in this repository is a slightly altered output of what was generated by SWIG. The code I used to generate it is:

cd ~/Projects/link-grammar/link-grammar-5.0.8/bindings/lisp
swig -cffi -module clinkgrammar -I../../link-grammar \
    -o ./clinkgrammar.lisp ../swig/link_grammar.i

I added the in-package code, but that’s about all I did. In fact, the link_grammar.i interface can be modified to do that automatically, so we probably shouldn’t version the clinkgrammar.lisp in the future, I am adding it here just to make sure we get the same or equivalent result. I think that if we want to continue to work on the bindings, than the best way to go about it would be to add (as little as possible) changes to the SWIG interface (which we could later ask the project developers to incorporate into their project), and to write the code that provides better abstraction to the C API separately. Maybe, for now, until the maintainers didn’t update the interface we could ourselves host the modified version of the interface.

Examples

I’ve copied this example from: www.abisource.com.

#include <locale.h>
#include <stdio.h>
#include "link-includes.h"

int main()
{
  Dictionary    dict;
  Parse_Options opts;
  Sentence      sent;
  Linkage       linkage;
  char *        diagram;
  int           i, num_linkages;
  char *        input_string[] = {
    "Grammar is useless because there is nothing to say -- Gertrude Stein.",
    "Computers are useless; they can only give you answers -- Pablo Picasso."};

  setlocale(LC_ALL, "");
  opts = parse_options_create();
  dict = dictionary_create_lang("en");
  if (!dict) {
    printf ("Fatal error: Unable to open the dictionary\n");
    return 1;
  }

  for (i=0; i<2; ++i) {
    sent = sentence_create(input_string[i], dict);
    sentence_split(sent, opts);
    num_linkages = sentence_parse(sent, opts);
    if (num_linkages > 0) {
      linkage = linkage_create(0, sent, opts);
      printf("%s\n", diagram = linkage_print_diagram(linkage, 1, 80));
      linkage_free_diagram(diagram);
      linkage_delete(linkage);
    }
    sentence_delete(sent);
  }

  dictionary_delete(dict);
  parse_options_delete(opts);
  return 0;
}

Below is the equivalent code in Lisp:

(in-package :link-grammar)

(defun test-hello-world ()
  (with-dictionary (en)
    (with-options (opts)
      (loop :for saying :in
         (list "Grammar is useless because there is nothing to say -- Gertrude Stein."
               "Computers are useless; they can only give you answers -- Pablo Picasso.")
         :do (with-sentence (sent saying)
               (split sent opts)
               (with-linkage (link)
                 (format t "~&diagram:~&~s" (print-diagram link))))))))