froth: FORTH for R

froth is a Forth implementation for R. If you’re new to froth or Forth, check out the detailed overview or my in-depth tutorial.

froth is distributed by CRAN. You can download it for your R installation by running:

install.packages("froth")

This implementation comes with a number of differences from other FORTHs:

• uses R operators for arithmetic, so 3 2 / returns 1.5
• arbitrary R objects can be pushed onto the stack
• built-in R print methods; use .R to format according to the print method for the top of the parameter stack
• obfuscated memory (no direct or emulated hardware-level memory access)
• no distinction between compiled and interpreted words (loops are possible outside of definitions!)
• Use of R lists for internal arrays; arrays of bytes are not supported
• ' will always look for the next token, not the next token from input stream. This makes it identical to ['] in function definitions. I may change this later.

This will (likely) not be a 1:1 copy of Gforth, I think I’d rather have a forth implementation that is robust and works in R than one that exactly imitates existing Gforth. But…tbd.

TODOs

• any kind of I/O functionality (though you can read files into froth from R)