FORTH-ish interpreter
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Prosper

Prosper is a Forth-like stack-based language. While taking specific influence from Forth, it does not attempt to emulate or implement the ANS Forth standards.

Currently, the language is entirely interactive -- to explore, simply run go run . in the root of this project and an interactive session will begin.

Syntax

Prosper is stack-based, as mentioned, so all the standard stack semantics are present:

> 1 2 3 4 + * -
ok
> .
-13 ok

New words can be defined using : ;:

> : SQUARE DUP * ;
ok
> 10 SQUARE .
100 ok

It has a single loop construct, DO LOOP:

> : TOFIVE 5 0 DO I . LOOP ;
ok
> TOFIVE
0 1 2 3 4 ok

Branches using IF ELSE THEN work:

> : EMOJI 0 < IF 128201 EMIT ELSE 128200 EMIT THEN ;
ok
> 100 EMOJI 
📈 ok
> -100 EMOJI
📉 ok

And, of course, it knows how to quit:

> BYE
bye

Future Plans

  • Implement VARIABLE and CONSTANT and the various ? ! @ related words
  • Implement SEE
  • Implement loading libraries of pre-written functions both from the command-line and at run-time
  • Add much better readline behaviors in the interactive console (up-arrow for history, cursor movement...)