PLFORTH represents a REPL and scripting language for the PLASMA environment. Or, what I did over the Holiday break.
The goals of PLFORTH are pretty straight forward:
**Interactivity** and **debugging**.
PLFORTH is a PLASMA module written in PLASMA itself. As a first class citizen of the PLASMA environment, it has instant access to all the PLASMA modules, from floating point to high-res graphics libraries and everything in between.
## Missing words in PLFORTH
There are quite a few missing word that a standard FORTH would have. Mostly due to deliberately keeping PLFORTH as minimal as possible to reduce the memory footpring and load time. Most of the missing words can be synthesized using existing PLASMA modules and some glue words. The double word have mostly been made avialable through PLASMA's 32 bit integer module, `INT32` by way of the `int32.4th` script. You can always petition to get your favorite FORTH word included in the default vocabulary. Speaking of `VOCABULARY`, PLFORTH only has one.
PLFORTH defaults to compiling using ITC (Indirect Threaded Code). This supports a list of inspection and debugging features while developing programs and scripts. However, the compiler can easily switch to PBC (PLASMA Byte Code) to greatly improve performance, but most of the debugging tools are lost. ITC compiled words and PBC compiled words can be intermingled and call each other seemlessly. PLASMA Byte Code is a direct match to many low-level FORTH constructs.
This is definitely a Work-In-Progress. There are still a few places where I'm unsure about the proper implementation of some words, especially the more esoteric compiler constructs. It also looks suspiciously like an early '80s wordset, as that is what I'm most familiar with.
## Links
Here is a (worse than usual) video running through some examples: https://youtu.be/picPyXAk77I?si=Td2En5Z3oxVTzh0z
A pre-configures ProDOS floppy image barely able to run PLFORTH is available here: https://github.com/dschmenk/PLASMA/blob/master/images/apple/PLFORTH.PO
