What implementation of Forth should I use for learning Forth? [closed]

Question

I want to start learning Forth (like in the related Stack Overflow question Is it practical to learn and use Forth?). I see that there are many implementations. I would like to use a

• ANS 1994 compatible version (if reasonable, but sticking to the standard might be good)
• small and compact implementation, I don't want a full OS.
• Windows
• easy to use, I am new to Forth ;-)

What particular implementation can be recommended?

Answer 1

Some time ago I evaluated 4tH, an implementation of Forth. I think it meets all of your requirements. For instance the compiler is only 61 KB. There is also full support for floating point numbers, important if you want to try to use it for technical/scientific purposes.

4tH runs on most operating systems, including MS-DOS, MS-Windows (both 16 bit and 32 bit), Linux, Coherent, AIX, SunOS, BOS, BSD, Mac OS X, BeOS, RISC OS, etc. Download (Windows installer, 1.5 MB, includes the manual). Manual (PDF, 1.1 MB).

There is an active community centered around the Google Group 4tH-compiler. For instance today I received two messages.

Please note that in 4tH you can't define your own defining words (words executing at compile time). This is not a serious limitation, unless you want to cover advanced Forth features.

---

To get you started (as this is not very clear from the manual or the interactive compile), after installation copy the compiler, 4th.exe, to an empty folder, make two files in this directory, HelloWorld.bat and HelloWorld.4th, and run HelloWorld.bat:

HelloWorld.bat:

    4th.exe cx HelloWorld.4th
    pause

HelloWorld.4th:

   : hello ." Hello from XYZ!" cr cr ;
   hello

Answer 2

Win32Forth is really fantastic, as mentioned above. It has a nice integrated development environment and is a pretty modern implementation that seems to match up very well with the standards as well as including some more experimental but widely-accepted features.

I use Gforth, but I also use Vim to edit source files. :) Gforth is good and "classic" as far as the features it supports. It gives you a very "old school" Forth experience without being overly quirky to use. (Some free Forths do odd things with their command lines and such - I use Brodie's "Starting Forth" as the model of how a Forth interpreter should behave.)

I looked at SwiftForth, which is a very nice "high tech" Forth system that goes well beyond what the classic Forths offer in terms of language features and really brings Forth into the modern programming world. If you want to actually do Forth programs professionally, SwiftForth looks like it can handle just about anything you want to do with it.

Answer 3

SwiftForth. It isn't self-consciously small and compact; it just happens to be. It's easy to use (LOCATE WH EDIT , a nicer than usual WORDS), comes with two books, and has an excellent mailing list with over a decade of archives. The evaluation version won't let you compile turnkey apps or DLLs; it still provides an excellent console for a student, and can support scripts in the usual ways. Quick Windows examples:

: sleep-monitor ( -- )
  HWND_BROADCAST WM_SYSCOMMAND SC_MONITORPOWER 2 SendMessage drop ;


library dnsapi.dll
( ... DLL imports, constants ... )
variable results
: DnsQuery ( z -- res )
  DNS_TYPE_A 0 NULL results NULL DnsQuery_UTF8 ;

: resolves? ( z -- f )
  DnsQuery if false exit then
  results @ DnsRecordListFree true ;


\ an example use of the dialog compiler
\ this compiled DSL is an example of something that 4th
\ precludes with its "not ... serious limitation"
DIALOG (HELLO-ABOUT)
[MODELESS " About Hello" 10 10 120 70
   (FONT 8, MS Sans Serif) ]
\  [class           text                        id   x   y   sx xy ]

   [CTEXT           " HELLO"                    -1  10  10  100 10 ]
   [CTEXT           " (C) 1997 Forth, Inc."     -1  10  25  100 10 ]
   [CTEXT           " http://www.forth.com"     -1  10  35  100 10 ]
   [DEFPUSHBUTTON   " OK"                     IDOK  35  50   50 14 ]
END-DIALOG

Answer 4

I realise they might not meet all your requirements but the following Forth-like languages might also interest you from a learning perspective.

• Factor
• RetroForth

Additionally, I have found the Re-Factor blog to be a good introduction to Factor.