3 ms·

> instead of one using e.g. .pg? Why not just `.prolog`? In this day and age. (Maybe there’s some reason like “then I can’t put these source files on FAT files

> instead of one using e.g. .pg? Why not just `.prolog`? In this day and age. (Maybe there’s some reason like “then I can’t put these source files on FAT filesystems”, I don’t know.) Java seems to do fine with it’s longer-than-three-letters `.java`.

Avshalom 4y ago
Most editors will understand .prolog, but on the other hand it's 15 years older than perl and it's not hard to teach editors to treat .pl as prolog.
anon291 4y ago
.pl is used because prolog is really old and FAT used to enforce extension limits. Not relevant nowadays, but it's stuck around.
- deleted 4y ago
  [deleted]
- pjmlp 4y ago
  FAT is 8 + 3, so it still had space for .pro as well.
  - infradig 4y ago
    Prolog is older than Perl. Perl usurped the .pl extension. Some are trying to claim it back.
    - eesmith 4y ago
      Yes, it looks like modern Prolog systems using ".pl". I checked Ciao, GNU Prolog (which recognizes ".pl" and ".pro"), SICStus Prolog (also ".pl" and .pro"), SWI-Prolog, and B-Prolog. The documentation for SWI-Prolog 5.10 (2010) even says "Tradition calls for .pl, but conflicts with Perl force the use of another extension on systems where extensions have global meaning, such as MS-Windows. On such systems .pro is the common alternative." https://www.swi-prolog.org/download/stable/doc/SWI-Prolog-5.10.0.pdf https://www.swi-prolog.org/download/stable/doc/SWI-Prolog-5..... Thing is, I can't confirm that tradition predates Perl 4 - call it 1993. Turbo Prolog used ".pro" in the late 1980s - https://archive.org/details/bitsavers_borlandturOwnersHandbook1987_8438592/page/n19/mode/2up?q=extension https://archive.org/details/bitsavers_borlandturOwnersHandbo... . So did Prolog-2, according to the 1990 book at https://archive.org/details/advancedlogicpro0000unse/page/80/mode/2up?q=extension https://archive.org/details/advancedlogicpro0000unse/page/80... . VPI Prolog from 1991 has an '".hc" file name extension (which stands for Horn Clause, the logic upon which the PROLOG language is based).'. I even found one Prolog system from that era using ".txt", at https://archive.org/details/programminginpro0000cloc/page/266/mode/2up?q=extension https://archive.org/details/programminginpro0000cloc/page/26... .
      - falsissime 4y ago
        The 1978 DEC10 Prolog user guide mentions PROG.PL as an example of a Prolog file with an extension. See 3.2 in https://userweb.fct.unl.pt/~lmp/publications/online-papers/USER%20GUIDE%20TO%20DECSYSTEM-10%20PROLOG.pdf https://userweb.fct.unl.pt/~lmp/publications/online-papers/U... Maybe the 1975 Prolog I manual has more to say...
        eesmith 4y ago
        Good work! I think it's even more explicit on p25 where it says "A module name can have the form either file.ext or just file. In the latter case the extension 'PL' is implied."

Avshalom 4y ago

Most editors will understand .prolog, but on the other hand it's 15 years older than perl and it's not hard to teach editors to treat .pl as prolog.

anon291 4y ago

.pl is used because prolog is really old and FAT used to enforce extension limits. Not relevant nowadays, but it's stuck around.

deleted 4y ago
[deleted]
pjmlp 4y ago
FAT is 8 + 3, so it still had space for .pro as well.
- infradig 4y ago
  Prolog is older than Perl. Perl usurped the .pl extension. Some are trying to claim it back.
  - eesmith 4y ago
    Yes, it looks like modern Prolog systems using ".pl". I checked Ciao, GNU Prolog (which recognizes ".pl" and ".pro"), SICStus Prolog (also ".pl" and .pro"), SWI-Prolog, and B-Prolog. The documentation for SWI-Prolog 5.10 (2010) even says "Tradition calls for .pl, but conflicts with Perl force the use of another extension on systems where extensions have global meaning, such as MS-Windows. On such systems .pro is the common alternative." https://www.swi-prolog.org/download/stable/doc/SWI-Prolog-5.10.0.pdf https://www.swi-prolog.org/download/stable/doc/SWI-Prolog-5..... Thing is, I can't confirm that tradition predates Perl 4 - call it 1993. Turbo Prolog used ".pro" in the late 1980s - https://archive.org/details/bitsavers_borlandturOwnersHandbook1987_8438592/page/n19/mode/2up?q=extension https://archive.org/details/bitsavers_borlandturOwnersHandbo... . So did Prolog-2, according to the 1990 book at https://archive.org/details/advancedlogicpro0000unse/page/80/mode/2up?q=extension https://archive.org/details/advancedlogicpro0000unse/page/80... . VPI Prolog from 1991 has an '".hc" file name extension (which stands for Horn Clause, the logic upon which the PROLOG language is based).'. I even found one Prolog system from that era using ".txt", at https://archive.org/details/programminginpro0000cloc/page/266/mode/2up?q=extension https://archive.org/details/programminginpro0000cloc/page/26... .
    - falsissime 4y ago
      The 1978 DEC10 Prolog user guide mentions PROG.PL as an example of a Prolog file with an extension. See 3.2 in https://userweb.fct.unl.pt/~lmp/publications/online-papers/USER%20GUIDE%20TO%20DECSYSTEM-10%20PROLOG.pdf https://userweb.fct.unl.pt/~lmp/publications/online-papers/U... Maybe the 1975 Prolog I manual has more to say...
      - eesmith 4y ago
        Good work! I think it's even more explicit on p25 where it says "A module name can have the form either file.ext or just file. In the latter case the extension 'PL' is implied."