Jedi Forth - Copyright 2015 Steven Goodwin

Released under the GNU GPL, version 3

This is a (very) simple implementation of Forth, using under 230 lines of Javascript. Including comments.

Why is it called 'Jedi'?

Because it was released on May the 4th 2015! I'm not apologizing for the bad pun, nor changing the name. (Until Disney sues me!)

Why?

I just wondered how small I could write an interpreter in Javascript, and still make it something worthwhile.

What's supported?

• Interpreted mode
• Compiled mode
• Trace debugging
• Conditionals (if-then-else)
• do loop and do +loop
• Print (.") and emit for output (input only via stack)
• A small, but workable, standard library

What's the vlist?

trace vlist dump 2/ 2* 2- 2+ 1- 1+ false true +loop loop do ; then else if 
<> = >= <= > < 0> 0< 0= r@ i r> >r emit spaces space cr ." . max min negate 
abs */ /mod mod / - * + pick 2dup ?dup dup rot over nip swap drop

Examples

Rocket countdown

: countdown   0 SWAP   DO  CR  I  .   -1  +LOOP  ;

use with

10 countdown

Factorial calculation

: factorial 1 + 1 1 rot rot do i * loop ;

use with

5 factorial

Solving quadratics

: QUADRATIC  >R SWAP ROT R@ *  + R> *  + ;

use with

2 7 9 3 QUADRATIC

TODO

• Properly support the return stack.
• Support ( comments )
• Support \ comments
• Add hex/decimal bases
• Contants : e.g. 13 CONSTANT ENTER-KEY
• Variables : along with @ ! and other memory-based stuff

Mising words

exit watch out begin again until while repeat case of endof endcase .. probably lots of others ..

Help with Forth

For language guides:

• http://www.forth.org/tutorials.html
• http://galileo.phys.virginia.edu/classes/551.jvn.fall01/primer.htm
• http://www.wulfden.org/downloads/Forth_Resources/SP_ProgrammingForth.pdf
• http://www.forth.com/starting-forth/sf6/sf6.html

For comparisons during development:

• http://home.diphi.com/users/jeffr/forth/jsforth.html

Apologies

Dear FIG - this is not worthy of your time. Sorry!