Trying to build a forth runtime in C
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forth/README.md

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Forth
=====
This is a new implementation of Forth 2012 in C.
Building & use
--------------
Use cmake or `build.sh`. It probably needs GCC with `--std=gnu99`.
You get a binary with the forth runtime. Run it to get a prompt. Use `-h` for help.
Goals
-----
- Comfy to use and extend
- No dynamic allocation where possible
- Compact and embeddable so it can be ported to ARM-CortexM or similar later
- Implement the CORE and CORE-EXT word sets, for a start
- Pass the [Forth2012 test suite](https://github.com/gerryjackson/forth2012-test-suite), at least for the word sets that are implemented
- Maybe eventually have some terminal-based implementation of (a subset of) the Facility word set, like AT-XY and keyboard input
- Try to keep added custom words and quirks at a minimum
- Comment stuff, maybe
Non-Goals
---------
- I don't really care about implementing some of the word sets
- Performance is not so critical for a hobby Forth like this
- Probably won't accept merge requests, this is my Forth
- I also don't care about someone telling me to add a license file
Custom words
------------
- `.\"` - like `."` but allows escaping, this is essentially `S\" blah" TYPE`, but without allocation (unless compiled)
- `??` - debug dump of the stacks
- `reset` - everything should become like if you restarted the program
- `debug ( flag -- )` - enable or disable verbose logging
For debug, there is `see ( "word" -- )` that lets you inspect and disassemble dictionary entries.
Implementation status
---------------------
*(this section may be outdated)*
Implemented and tested:
```
CORE:
! ' ( * */ */MOD + +! +LOOP , - . ." # #> #S <# >BODY >NUMBER / /mod 0< 0= 1+ 1- 2! 2* 2/ 2@ 2DROP 2DUP 2OVER 2SWAP
: ; < = > >IN >R ?DUP @ ABORT ABS ALIGN ALIGNED ALLOT AND BASE BEGIN BL C! C, C@ CELL CELL+ CELLS CHAR CHAR+
CHARS CONSTANT COUNT CR CREATE DECIMAL DEPTH DO DOES> DROP DUP ELSE EMIT ENVIRONMENT? EXECUTE EXIT FILL FM/MOD FIND
HERE HOLD I IF IMMEDIATE INVERT J LEAVE LITERAL LOOP LSHIFT M* MAX MIN MOD MOVE NEGATE OR OVER POSTPONE QUIT R> R@ RECURSE
REPEAT ROT RSHIFT S>D S" SIGN SM/REM SOURCE SPACE SPACES STATE SWAP THEN TYPE U. U< UNTIL UM* UM/MOD UNLOOP VARIABLE WHILE WORD XOR [ ['] [CHAR] ]
CORE-EXT:
.( :NONAME 0<> 0> 2>R 2R> 2R@ <> ?DO AGAIN FALSE HEX NIP PAD PICK ROLL S\" TO TRUE TUCK U.R U> UNUSED VALUE
\
Other sets:
FORGET SEE BYE
```
Missing:
```
CORE:
ABORT" ACCEPT EVALUATE KEY
CORE-EXT:
.R ACTION-OF BUFFER: C" CASE COMPILE, DEFER DEFER! DEFER@ ENDCASE ENDOF ERASE HOLDS IS
MARKER OF PARSE PARSE-NAME REFILL RESTORE-INPUT SAVE-INPUT SOURCE-ID WITHIN [COMPILE]
```
.