reborg / clorth

A Clorth in Clojure

Clorth

A Forth implementation in Clojure. Currently implementing a limited subset of the standard library but already provided with interop to call into Clojure standard library. Clone the project, start the repl with lein repl and then type @clorth to start the interpreter. An extended introduction is also available in these slides.

Your first Forth program

Start the REPL with clj and then type @clorth to start the Clorth interpreter. The following is a small Forth program coming from the first chapter of Starting Forth. Please type every line at the prompt and hit the key. The following are all words definitions and they start with ":" and end with ";":

: star 42 emit;
: stars 0 do star loop;
: margin cr 30 spaces;
: dot margin star;
: line margin 5 stars;

We just created a small "fun" language:

line dot line dot dot cr
                             *****
                             *
                             *****
                             *
                             *

Let's create one last word so we can just type the single letter "F":

: F line dot line dot dot cr
F
                             *****
                             *
                             *****
                             *
                             *

Interop

Clorth allows deep integration with Clojure. To call a function in the Clojure standard library, you need to use the _ (underscore) operator. By default, what follows _ is resolved in the clorth.core namespace and invoked on the first element on the stack:

1 2 3 _ inc .
> 4