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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:


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 exacly imitates existing Gforth. But…tbd.


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