222 lines
7.9 KiB
Text
222 lines
7.9 KiB
Text
This is the file README and belongs to version 0.9.4a of May 8, 1994
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of the portable Forth-environment.
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--------------------------------------------------------------------
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What is it?
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===========
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This package contains all neccessary ANSI-C source files to build a
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running Forth-environment on most UNIX machines, on DOS and on OS/2.
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The Forth-system is closely modeled along the new American National
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Standard for the programming language Forth. I implemented every word
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of every word set mentioned in the dpANS-6 document of june 1993.
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Additionally it is compatible to Forth-83.
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This set of source files is distributed under the GNU general public
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license for libraries. See the file COPYING.LIB for conditions.
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I chose that one to point out that I don't consider programs you write
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on top of it a 'derived work' of the portable Forth environment. To
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violate these conditions you have to do two things together:
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- you use a modified pfe to run your program
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- you keep these modification secret
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Should be easy to avoid.
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Why did I do it?
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================
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For fun. As an excercise in unix programming. And there was no such
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thing. See below, design objectives.
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Design objectives
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=================
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With two elaborate standards at hand, one for C, one for Forth, it
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should be possible to build one language in terms of the other and
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thus provide both where at least one is available.
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While I leave the writing of an ANSI-C compiler in Forth to those who
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really believe in Forth's superiority and universality, I concentrated
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on the manageable part: Providing a Forth-system in ANSI-C that is
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- CORRECT this means not just "no bugs" -- it means all
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the interaction of all parts works as specified
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by the standard AND by traditions.
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- COMPLETE with powerful computers on the desk and power-
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ful programming environments there is no need
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to and no use in strategies like "here kernel,
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there xyz word set" that might be appropriate
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on a microcontroller.
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- PORTABLE I hate to rewrite code because of environmental
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dependencies. Most of the system should be a mere
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interface between two well defined languages.
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There are of course such dependencies. I tried
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to resort to a common subset of all UNIX bahavior
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known to me. Fortunately this in fact allowed
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porting to DOS and OS/2 thanks to the great
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emx-package.
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- USABLE A sole kernel helps noone. It should be a
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development environment. You should be able
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to manage multiple-source-file-projects from
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within.
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- SIMPLE or transparent. At least to my taste.
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Maybe you miss the design objective SPEED. It was not my goal to
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provide the fastest C-based Forth-environment. This would have led to
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conflicts with much more important goals. We all have fast computers,
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haven't we?
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After all pfe isn't slow. With a little tuning using GNU-C's global
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register variable feature it is pretty fast. But obviously it cannot
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compete with assembler implementations.
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Status
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======
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Did I achieve the above objectives?
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Some of them. I'll continue working on it.
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The system is in use for fifteen month now. Several quite obvious and
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several quite subtle bugs have been fixed. While there surely are some
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more, they are not as obvious since the system passes several test
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programs, some of them rather sophisticated.
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Once you get the system running, you'll have
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- All ANSI Forth word sets with the exception of the assembler
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hooks `CODE', `END-CODE' etc. Nothing else is missing.
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- Several more words provided for compatibility and convenience.
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- An interface to a text editor to edit plain text sources
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and the ability to include them.
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- A word star lookalike block file editor to write
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source in the old style block format.
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- A simple source level debugger -- maybe I should better
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say "single stepper".
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Thus you'll be able to edit, compile an run programs in a moderately
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comfortable way. For the final design of the development environment
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your suggestions still are welcome!
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If you try this system, please keep in mind that it is still under
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development. Sometimes new --even stupid-- bugs are introduced while
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enhancing functionality or while fixing old ones. I appreciate every
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hint to a bug and I fixed every bug I've been told about in the last
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months. So please don't hesitate to tell me about whatever seems
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wrong. Please check for the latest version via anonymous ftp from
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roxi.rz.fht-mannheim.de:/pub/languages/forth/pfe-?.?.?.tar.gz
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(accessible from germany only) or
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sunsite.unc.edu:/pub/languages/forth/pfe-?.?.?.tar.gz
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Please send suggestions and bug reports via e-mail to
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duz@roxi.rz.fht-mannheim.de
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Usage
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=====
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For installation refer to the files `install' and `tuning'.
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Once you have it running and see the "ok" prompt after typing return
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you can interactively type in forth words. If you mistype, you can
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edit the command line and recall old command lines with the arrow
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keys. (If you can't then your termcap doesn't work all right and you
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can resort to wordstar-like control keys.)
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To write some more statements try "EDIT-TEXT filename". This will
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invoke your favorite text-file editor on the given file. If it
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doesn't, first check the environment variable EDITOR, then check the
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file "const.h" for the #defined symbol "EDITOR".
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Having written some code you can load it by "INCLUDE filename".
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If you prefer the old style block files, give a file to use as
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block-file with the -b commandline option. Alternatively you can say
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`USING filename' or if the file doesn't exist yet: `USING-NEW
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filename'. Then you can edit a block by `n EDIT-BLOCK'.
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If your termcap-mechanism works well, the arrow keys and some other
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function keys should be active. Quit the editor with ^U and load
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blocks with "n LOAD". If it doesn't work well you might not even get a
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picture.
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For more commandline options try the option -h.
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The interrupt key is remapped to ^U and leads back to the FORTH input
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loop. Use it to break out of infinite loops.
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To terminate the system, type BYE at the command-prompt or press the
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keyboard quit key of your system (usually ^\).
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Documentation
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=============
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I started writing a documentation in texinfo format. This will allow
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you to view it online or print it in good quality. There's also an
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outdated and hopefully soon superseded man-page that explains some of
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the command line options. All documentation is highly unfinished.
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For more information please try to get the dpANS-document, which is
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an EXCELLENT REFERENCE to this system! You can (could?) ftp it at
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ftp.uu.net in the directory /vendor/minerva/x3j14.
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Contributions
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=============
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are welcome! After the kernel is finished now it makes much sense to
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share the burden of creating and improving a well rounded programming
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environment for all tasks a Forth programmer wants to do. PFE is YOUR
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tool. Get involved in it's design!
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There is a mailing list on pfe which you should subscribe to if you
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want to be up to date with the development of the system. Send e-mail
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to duz@roxi.rz.fht-mannheim.de if you want to subscribe to that
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mailing list.
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Acknowledgements
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================
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I want to express my gratitude to the people who put their efforts in
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the precise descriptions I found in these documents:
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- draft proposed American National Standard -- Programming Languages
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-- Forth (X3J14 dpANS-6, June 30, 1993)
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- FORTH-83 Standard (August 1983)
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- fig-FORTH Installation Manual -- Glossary, Model, Editor
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(Version 1.3, November 1980)
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Thanks for providing superb development tools:
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- Richard Stallman and the FSF, Linus Thorvalds and all who
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contribute to Linux and Eberhard Mattes.
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Several nice people gave me valuable hints to bugs and possible
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improvements, were patient enough to try the very first releases, made
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ports to machines I never saw myself and kept me from frustration. If
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pfe is stable now it is thanks to it's users. Most notably:
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Lennert Benschop, Sean Conner, Holger Dietze, Kevin Haddock,
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Rob Hooft, Giorgio Richelli, Marko Teiste, Guenther Thomsen.
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Thank You.
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