This project builds but has little functionality. It discredited its original hypothesis.

The starting hypothesis,

That a gas-powered forth engine would be useful as a general-purpose
interpreter to be embedded in larger systems.

The 'gas' concept serves the same role as Ethereum gas,

The enclosing system periodically gives an amount of 'gas' to our
interpreter that is consumed as it runs.

In this respect, the machine is technically not a turing machine, and
cannot get into infinite loops.

Through work, I formed a conclusion that there are better approaches to create a gas-powered interpreter. For example, a better approach would be to create a gas-powered virtual machine (either stack or register-based) and them to implement forth on top of that.

There was a further design error in the implementation of the stack here,

Implementation of the stack is done via pooling of malloc'd blocks.

The design would be tighter if the stack used the same memory space as the
dictionary. Each could grow from different ends. Other forth systems use
this approach.

Copyright (c) 2020, Craig Turner

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.