[OT] Eternal programming

[Roman Suzi]

On Tue, 10 Jul 2001, Mikael Olofsson wrote:

> INTERCAL or Brainf***, anyone?

The following script was written in half an hour 
(after I found this page:

http://chemlab.pc.maricopa.edu/pocket/pfmanual.html

(Chemists are going to use Forth in nanotech programming. ;-) 

#!/usr/bin/python
# -*- mode: python -*-
# future core Eternal/Python implementation ;-)
# This code is in Public Domain
# $Id:$

global defining, stack, dictionary, executionstack

defining = 0

def _DOT():
  global stack
  try:
    v = stack.pop()
    print v
    return 1
  except:
    return None

def _ADD():
  global stack
  try:
    v2 = stack.pop()
    v1 = stack.pop()
    stack.append(v1+v2)
    return 1
  except:
    return None

stack = []
dictionary = {
  "." : {'immediate': 0, 'body': _DOT},
  "+" : {'immediate': 0, 'body': _ADD},
  }

def isnumber(x):
  try:
    int(x)
  except:
    return None
  return x

def builtin(word):
  return type(word['body']) == type(builtin)

def SEARCH(token):
  global dictionary
  try:
    return dictionary[token]
  except:
    return None

def EXECUTE(word):
  if builtin(word):
    return word['body']()
  else:
    return INTERPRETE(word['body'])

def EMPTYSTACK():
  raise "Empty stack"

def WHAT_IS_IT():
  raise "???"

def COMPILE(token):
  pass

def LITERAL(token):
  pass
  
def INTERPRET(tokens):
  global defining, stack
  for token in tokens:
    found = SEARCH(token)
    if found:
      if not defining or found['immediate']:
        if not EXECUTE(found):
          EMPTYSTACK()
      else:
        COMPILE(token)
    else:
      if isnumber(token):
        if not defining:
          stack.append(int(token))
        else:
          LITERAL(token)
      else:
        WHAT_IS_IT(token)
  return 1    

INTERPRET(["1", "2", "+", "."])

# End of interpreter.py

TODO:
 - executionstack instead of Python-based recursion
 - compiling part of the story
 - what is MCOMPILE and is it useful enough to complicate things? 
 - token reader
 - where globals should live? (multithreading-safely)
 - error handling

It needs courage to replace Forth's machine-code orientedness into
very-high Python structures ;-) I just can't decide if I want to emulate
memory arrays or do it in free fashion ;-)

Sincerely yours, Roman A.Suzi
-- 
 - Petrozavodsk - Karelia - Russia - mailto:rnd at onego.ru -