minimal 1.0.0
Minimal Forth Workbench provides an educational subset of Standard Forth, feel free to experiment.
Minimal Forth Workbench
Ulrich Hoffmann uho@xlerb.de
Version 1.0.0 - 2015-10-10
This package provides a workbench implementation of Minimal Forth as proposed by Paul Bennett and Peter Knaggs at EuroForth 2015 in Bath.
Their aim is to define a Standard Forth subset suitable for educational purposes. For this they propose to cut down the number of Forth words initially explained to Forth newcomers and only stepwise introduce new concepts such as number output, compiling words, strings, file access, exceptions, ...
This package - the Minimal Forth Workbench - allows to experiment with different sets of primitive (i.e. predefined) definitions in order to further elaborate on Paul's and Peter's ideas.
Implementation
This implementation picks the appropriate words from a Standard (Forth 94 oder Forth
2012) system (the so called host system) and puts them in a wordlist of their own
named minimal
.
In the end, this wordlist is defined to become the only wordlist in the search
order and also the current wordlist. In essence this makes all other word definitions
from the host system unavailable to the Minimal Forth Workbench.
The source code is seperated into several files:
The primitive words of Minimal Forth, to take from the host system. They are defined in the file
primitives.fs
Words of Minimal Forth that can be defined in terms of primitives and other Minimal Forth words, i.e. "All that can be built from the primitives". They are defined in the file
prelude.fs
The implementation of the word
PRIMITIVE
and the overall setup: fileminimal.fs
.
As currently setup, the words defined in primitives
and prelude
are exactly
the words proposed by Paul and Peter with 69 Minimal Forth words.
In addition the words INCLUDE
, WORDS
, PRIMITIVE
, and BYE
that we consider more development environment than language are available.
They are not included in the primitives and word counts.
Many other definitions are currently commented out, such as
POSTPONE
, IMMEDIATE
, >BODY
, SLITERAL
, LITERAL
, and COMPILE,
which
are the basis of compiling words like S"
´, AGAIN
or ?EXIT
.
Your are invited to experiment: remove or add primitives or modífy, add, remove definitions in prelude
.
Please, share your findings.
Installation
To use the Minimal Forth workbench just INCLUDE minimal.fs
on any standard system. This makes
the Minimal Forth definitions and only them available. After loading, all defined words still
have their standard meaning - however Minimal Forth is no standard system itself
as it does not provide all definitions from the CORE word set.
Example usage
$ sf minimal.fs
Minimal Forth Workbench: 48 primitives, 69 words
ok
words ALIGNED CELL+ CHAR+ ROT 2/ LSHIFT XOR OR > = 0= TRUE FALSE MOD 2* / * + VARIABLE
CONSTANT DUP primitive WORDS INCLUDE bye \ .S ( CR KEY? EMIT KEY DOES> ; CREATE :
EXECUTE J LOOP UNTIL AGAIN BEGIN ELSE ' I DO REPEAT WHILE THEN IF R> OVER DROP R@ >R
SWAP RSHIFT INVERT AND < - */MOD CHARS CALIGNED CALIGN C@ C, C! CELLS ALIGN @ , !
48 primitives, 69 words ok
Bug Reports
Please send bug reports, improvements and suggestions to Ulrich Hoffmann <uho@xlerb.de>
Conformance
This program conforms to Forth-94 and Forth-2012. It has been verified to load succesfully on SwiftForth, iForth and gForth.
May the Forth be with you!