JoySON - a tiny concatenative programming language with JSON syntax

helloworld.json

{
  "main": ["lit", "Hello, world!", "print"]
}

joyson.py

#!/usr/bin/env python3
import json
import sys

class env:
    def __init__(self, mem=[]):
        self.ds = []
        self.rs = []
        self.ip = 0
        self.mem = mem
        self.dict = dict

    def dup(self):
        self.ds.append(self.ds[-1])

    def drop(self):
        self.ds.pop()

    def swap(self):
        x = self.ds.pop()
        y = self.ds.pop()
        self.ds.append(x)
        self.ds.append(y)

    def lit(self):
        self.ds.append(self.mem[self.ip])
        self.ip += 1

    def dip(self):
        block = self.ds.pop()
        value = self.ds.pop()
        oldmem = self.mem
        oldip = self.ip
        def kont(self):
            self.mem = oldmem
            self.ip = oldip
            self.ds.append(value)
        self.mem = block
        self.ip = 0
        self.rs.append(kont)

    def print(self):
        print(self.ds.pop())

    def call(self, val):
        if callable(val):
            val(self)
        elif isinstance(val, str):
            word = self.dict[val]
            if callable(word):
                word(self)
            elif isinstance(word, list):
                oldmem = self.mem
                oldip = self.ip
                def kont(self):
                    self.mem = oldmem
                    self.ip = oldip
                self.rs.append(kont)
                self.mem = word
                self.ip = 0
            else:
                raise TypeError("unexpected definition:", val, "->", word)
        else:
            self.ds.append(val)

    def run(self):
        while True:
            if self.ip < len(self.mem):
                word = self.mem[self.ip]
                self.ip += 1
                self.call(word)
            elif len(self.rs) > 0:
                k = self.rs.pop()
                k(self)
            else:
                break
        return self

dict = {
    "dup": env.dup,
    "drop": env.drop,
    "swap": env.swap,
    "lit": env.lit,
    "dip": env.dip,
    "print": env.print,
}

with open(sys.argv[1], "r") as fp:
    code = json.load(fp)
    dict.update(code)

e = env(["main"]).run()
if e.ds:
    print(e.ds)