Simple code-golf programming language written in Python

Question

I've written a "simple" interpreter for a programming language in Python, called Tellurium (named after the element of the same name). So far, it's working pretty well, but there are some things I'd like to fix/remove.

Tellurium is a tape-based language, so it uses a tape to store data.

import string, sys, random, time, codecs
tape = [0] * 25500
funcs = {}
variables = {}
readingStr = False
readingLoopAmount = False
readingLoopCode = False
readingRand = False
readingRand2 = False
readingFName = False
readingFCode = False
readingName = False
readingVName = False
readingFileName = False
readingVText = False
readingVName2 = False
appendToFront = False
appendToBack = False
loopInf = False
loopRand = False
string = False
isChar = False
fileName = []
vName = []
vText = []
vName2 = []
tempText = []
tempName = []
fName = []
fCode = []
text = []
rand = []
rand2 = []
loopCode = []
loopAmount = []
selected = 0
def prompt():
 cmd = input("> ")
 return cmd
def read(cmd):
 if "!K" in cmd:
 cmd = cmd.replace("!K", "1000")
 if "!H" in cmd:
 cmd = cmd.replace("!H", "100")
 commands = len(cmd)
 tokens = list(cmd)
 for i in range(0, commands):
 parse(tokens[i])
def parse(cmd):
 # Sorry for all these globals...
 global tape
 global funcs
 global variables
 global readingStr
 global readingFileName
 global readingLoopAmount
 global readingLoopCode
 global readingRand
 global readingRand2
 global readingFName
 global readingFCode
 global readingName
 global readingVName
 global readingVText
 global readingVName2
 global appendToFront
 global appendToBack
 global loopInf
 global loopRand
 global vName, vText, vName2
 global fileName
 global string
 global isChar
 global tempName
 global tempText
 global fName
 global fCode
 global text
 global rand
 global rand2
 global loopCode
 global loopAmount
 global selected
 if readingFileName == True:
 if cmd == "]":
 readingFileName = False
 f = open(''.join(fileName), 'r')
 code = f.read()
 f.close()
 read(code)
 fileName = []
 else:
 fileName.append(cmd)
 elif readingVName2 == True:
 if cmd == ".":
 readingVName2 = False
 tape[selected] = variables[''.join(vName2)]
 vName2 = []
 else:
 vName2.append(cmd)
 elif readingVName == True:
 if cmd == "|":
 readingVText = True
 readingVName = False
 else:
 vName.append(cmd)
 elif readingVText == True:
 if cmd == "]":
 readingVText = False
 name = ''.join(vName)
 val = ''.join(vText)
 variables[name] = val
 vName = []
 vText = []
 else:
 vText.append(cmd)
 elif readingName == True:
 if cmd == ".":
 readingName = False
 name = ''.join(tempName)
 read(funcs[name])
 tempName = []
 else:
 tempName.append(cmd)
 elif readingFName == True:
 if cmd == "|":
 readingFName = False
 readingFCode = True
 else:
 fName.append(cmd)
 elif readingFCode == True:
 if cmd == "`":
 readingFCode = False
 name = ''.join(fName)
 code = ''.join(fCode)
 funcs[name] = code
 fName = []
 fCode = []
 else:
 fCode.append(cmd)
 elif readingRand == True:
 if cmd == "|":
 readingRand = False
 else:
 rand.append(cmd)
 elif readingRand2 == True:
 if cmd == "|":
 readingRand2 = False
 else:
 rand2.append(cmd)
 elif string == True:
 if appendToFront == True:
 if cmd == "~":
 tape[selected] = str(tape[selected]) + ''.join(tempText)
 tempText = []
 appendToFront = False
 elif cmd == "$":
 tape[selected] = str(tape[selected]) + str(tape[selected-1])
 appendToFront = False
 tempText = []
 else:
 tempText.append(cmd)
 elif appendToBack == True:
 if cmd == "~":
 tape[selected] = ''.join(tempText) + str(tape[selected])
 tempText = []
 appendToBack = False
 elif cmd == "$":
 tape[selected] = str(tape[selected-1]) + str(tape[selected])
 appendToFront = False
 tempText = []
 else:
 tempText.append(cmd)
 elif cmd == "r":
 tape[selected] = tape[selected].reverse()
 elif cmd == "u":
 tape[selected] = tape[selected].upper()
 elif cmd == "l":
 tape[selected] = tape[selected].lower()
 elif cmd == "a":
 appendToFront = True
 elif cmd == "b":
 appendToBack = True
 elif cmd == ".":
 string = False
 elif readingLoopAmount == True:
 if cmd == "|":
 readingLoopAmount = False
 readingLoopCode = True
 elif cmd == "i":
 loopInf = True
 elif cmd == "r":
 loopRand = True
 else:
 loopAmount.append(cmd)
 elif readingLoopCode == True:
 if cmd == "]":
 readingLoopCode = False
 if loopInf == True:
 while 1:
 read(loopCode)
 if loopRand == True:
 if rand and rand2 == []:
 for i in range(0, random.randint(0, 100)):
 read(loopCode)
 else:
 if rand2 == []:
 for i in range(0, random.randint(0, int(''.join(rand)))):
 read(loopCode)
 elif rand == []:
 for i in range(0, random.randint(int(''.join(rand2)), 100)):
 read(loopCode)
 else:
 for i in range(0, random.randint(int(''.join(rand2)), int(''.join(rand)))):
 read(loopCode)
 else:
 for i in range(0, int(''.join(loopAmount))):
 read(loopCode)
 loopCode = []
 loopAmount = []
 else:
 loopCode.append(cmd)
 elif readingStr == True:
 if cmd == "~":
 readingStr = False
 text = ''.join(text).replace("μ", "")
 tape[selected] = text
 text = []
 else:
 text.append(cmd)
 elif cmd == "+":
 tape[selected] += 1
 elif cmd == "-":
 tape[selected] -= 1
 elif cmd == ">":
 selected += 1
 elif cmd == "<":
 selected -= 1
 elif cmd == "*":
 print(selected)
 elif cmd == "^":
 print(tape[selected])
 elif cmd == "!":
 if isinstance(tape[selected], str):
 print(tape[selected])
 else:
 print(chr(tape[selected]))
 elif cmd == "%":
 tape[selected] = ord(tape[selected])
 elif cmd == "#":
 tape[selected] = 0
 elif cmd == "$":
 selected = 0
 elif cmd == "/":
 tape[selected] += 10
 elif cmd == "\\":
 tape[selected] -= 10
 elif cmd == "{":
 selected += 10
 elif cmd == "}":
 selected -= 10
 elif cmd == '"':
 tape[selected] += 100
 elif cmd == "'":
 tape[selected] -= 100
 elif cmd == "-":
 selected += 100
 elif cmd == "_":
 selected -= 100
 elif cmd == "i":
 tape[selected] = input(">> ")
 elif cmd == "n":
 tape[selected] = int(tape[selected])
 elif cmd == "a":
 tape[selected] = int(tape[selected]) + int(tape[selected+1])
 elif cmd == "s":
 tape[selected] = int(tape[selected]) - int(tape[selected+1])
 elif cmd == "m":
 tape[selected] = int(tape[selected]) * int(tape[selected+1])
 elif cmd == "d":
 tape[selected] = int(tape[selected]) / int(tape[selected+1])
 elif cmd == "(":
 readingNum = True
 elif cmd == "z":
 tape[selected] = tape[selected+1]
 elif cmd == "x":
 tape[selected] = tape[selected-1]
 elif cmd == "μ":
 readingStr = True
 elif cmd == "[":
 readingLoopAmount = True
 elif cmd == "p":
 return
 elif cmd == ".":
 exit
 elif cmd == "&":
 string = True
 elif cmd == "→":
 if rand != []:
 rand = []
 readingRand = True
 elif cmd == "←":
 if rand2 != []:
 rand2 = []
 readingRand2 = True
 elif cmd == "t":
 tape[selected] = str(time.ctime())
 elif cmd == " ̈":
 time.sleep(1)
 elif cmd == "r":
 tape[selected] = codecs.encode(str(tape[selected]), 'rot_13')
 elif cmd == "n":
 tape[selected] = int(tape[selected])
 elif cmd == "@":
 readingFName = True
 elif cmd == "=":
 readingName = True
 elif cmd == "¤":
 readingVName = True
 elif cmd == ";":
 readingVName2 = True
 elif cmd == "0":
 readingFileName = True
 elif cmd == "f":
 tape[selected] = float(tape[selected])
while 1:
 read(prompt())

Example programs

• Hello, world! - μHello, world!~^

  Explanation: everything after μ and before ~ will be read and stored in the tape's currently selected cell. ^ outputs whatever is in the selected cell, which in the program is Hello, world!.

• Cat program - i^

  Explanation: i reads input and stores it in the selected cell. ^ outputs whatever is in the cell.

• Navigating cells - +>++>+++<<^>^>^

  Explanation: + adds one to the selected cell's value. > goes forward one cell in the tape. < goes back, and ^ outputs whatever is in the selected cell. So, the output is 123, separated by newlines.

• Math (addition) - +>+<a^

  Explanation: If you read the above example, you'll know what the +, > and < commands do. The a command is the addition command. It takes the values of the selected cell and the next one up, and adds them together. The result is stored in the selected cell. The other math commands are s (subtraction), m (multiplication) and d (division).

• Loop - [5|^]

  Explanation: The syntax of a for loop in Tellurium is [times|code]. So, this outputs the selected cell's value 5 times.

• Clock - [i|t^ ̈]

  Explanation: t stores the current time and date in the selected cell. ̈ waits one second before continuing the code. i makes a loop run forever. The code will keep printing the current time and date every second.

• Countdown - /[10|-^ ̈]

  Explanation: / adds ten to the selected cell's value. The loop after that runs the code -^ ̈ ten times. - subtracts one from the cell's value.`

• Functions - @a|^^^^]

  Explanation: this program creates a function called a, which outputs the selected cell's value four times.

• Calling functions - =a.

  Explanation: this calls a function called a. (The . is needed, otherwise it won't work)

• Appending to strings - μHello,&aworld!~.^`

  Explanation: this sets the value of the selected cell to Hello,. & starts string manipulation mode. While in string mode, you can use the a command to append to the end of a string. In this example, it appends world! to the end of the selected cell..` exits string manipulation mode.

---

The reason I posted this here is because the code is messy and quite unreadable. I'm looking for some tips to clean it up, remove the unneeded things, etc. Also, I'd like to remove the big list of variables and global statements, if possible. They're limiting the flexibility of the language. For example, I can't implement conditional statements until I've removed the globals. I've tried, but it hasn't worked.

Answer 1

Seeing as it's a long post, I'll just see where I can get, starting now.

First, prompt:

def prompt():
 cmd = input("> ")
 return cmd

You don't need the intermediate variable. Just write this:

def prompt():
 return input("> ")

Also, you only use it once, so why not use input("> ") instead of prompt()?.

Next, read:

def read(cmd):
 if "!K" in cmd:
 cmd = cmd.replace("!K", "1000")
 if "!H" in cmd:
 cmd = cmd.replace("!H", "100")
 commands = len(cmd)
 tokens = list(cmd)
 for i in range(0, commands):
 parse(tokens[i])

The if checks can be gone, because otherwise .replace is just a no-op. (It might matter for efficiency, perhaps!). That leaves us with

def read(cmd):
 cmd = cmd.replace("!K", "1000")
 cmd = cmd.replace("!H", "100")
 commands = len(cmd)
 tokens = list(cmd)
 for i in range(0, commands):
 parse(tokens[i])

Also, looping over a string gives us a list of characters. Using that, we get

def read(cmd):
 if isinstance(cmd, str):
 cmd = cmd.replace("!K", "1000")
 cmd = cmd.replace("!H", "100")
 for token in cmd:
 parse(token)

Which reads a bit saner. The isinstance is needed, because cmd is sometimes a list, and that does not have a replace method. (Alternatively, make sure read is always called with a str).

Binary int operations.

Browsing down further, I see the following interesting piece of code:

elif cmd == "a":
 tape[selected] = int(tape[selected]) + int(tape[selected+1])
elif cmd == "s":
 tape[selected] = int(tape[selected]) - int(tape[selected+1])
elif cmd == "m":
 tape[selected] = int(tape[selected]) * int(tape[selected+1])
elif cmd == "d":
 tape[selected] = int(tape[selected]) / int(tape[selected+1])

See the repetition? This is easily fixable, add the following to the top of your module:

import operator
INT_BINOPS = {
 "a": operator.add,
 "s": operator.sub,
 "m": operator.mul,
 "d": operator.truediv, # Maybe you meant floordiv?
}

and replace the elif change with

elif cmd in INT_BINOPS:
 op = INT_BINOPS[cmd]
 tape[selected] = op(int(tape[selected]), int(tape[selected + 1]))

in-place unary operations

Next, I moved the cases for /, \, ", ', n, % closer together to bring out the similarity:

elif cmd == "/":
 tape[selected] += 10
elif cmd == "\\":
 tape[selected] -= 10
elif cmd == '"':
 tape[selected] += 100
elif cmd == "'":
 tape[selected] -= 100
elif cmd == "n":
 tape[selected] = int(tape[selected])
elif cmd == "%":
 tape[selected] = ord(tape[selected])

Reading carefully, all have the form

tape[selected] = f(tape[selected])

for proper functions f. Let's apply the same trick. Using lambda because

import functools
INPLACE_UNARYOPS = {
 "+": functools.partial(operator.add, 1),
 "-": functools.partial(operator.add, -1), # can't use .sub here
 "/": functools.partial(operator.add, 10),
 "\\": functools.partial(operator.add, -10), # can't use .sub here
 '"': functools.partial(operator.add, 100),
 "'": functools.partial(operator.add, -100), # can't use .sub here
 "n": int,
 "%": ord,
}

and then in the elif chain use

elif cmd in INPLACE_UNARYOPS:
 op = INPLACE_UNARYOPS[cmd]
 tape[selected] = op(tape[selected])

(funnily enough, you actually have "n" twice, I just removed one of them).

Furthermore, I also added "r" and "f" to the dictionary as follows (because I missed those):

 "r": lambda v: codecs.encode(str(v), 'rot_13'),
 "f": float,

Assignment from nowhere

There are also "t", "i" and "#" which look alike. They get the same treatment as before. At the top:

FUNCS = {
 "t": lambda: str(time.ctime()),
 "#": lambda: 0,
 "i": lambda: input(">> "),
}

And in the if-chain:

elif cmd in FUNCS:
 tape[selected] = FUNCS[cmd]()

Uniform position logic

Again, make things simple. Move similar things together:

elif cmd == "$":
 selected = 0
elif cmd == ">":
 selected += 1
elif cmd == "<":
 selected -= 1
elif cmd == "{":
 selected += 10
elif cmd == "}":
 selected -= 10
elif cmd == "-":
 selected += 100
elif cmd == "_":
 selected -= 100

You can probably expect the drill:

POSITION_ACTIONS = {
 "$": lambda _: 0,
 ">": functools.partial(operator.add, 1),
 "<": functools.partial(operator.add, -1),
 "{": functools.partial(operator.add, 10),
 "}": functools.partial(operator.add, -10),
 "-": functools.partial(operator.add, 100),
 "_": functools.partial(operator.add, -100),
}

And the handler:

elif cmd in POSITION_ACTIONS:
 selected = POSITION_ACTIONS[cmd](selected)

Make sure it is later than the value-actions, because you re-used "-" (bug?).

Complex logic

Now, the above changes were fairly trivial (but beneficial!). You can probably handle some extra cases as well.

But there's also a bit of complex logic.

I'm not sure if I'm going in the right direction, so bear with me for a while.

First, I'll rename parse to _parse, and define a function parse as follows:

def parse(token):
 return _parse(token)

Please convince yourself that this changes nothing.

Next, I'm going to change that again to

parser_stack = [_parse]
def parse(token):
 parser_stack[-1](token)

Again, this should not change anything.

And now I'll show you why: we're going to replace the readFileName case. First we add the function

def read_filename(cmd):
 global fileName
 if cmd == "]":
 parser_stack.pop()
 f = open(''.join(fileName), 'r')
 code = f.read()
 f.close()
 read(code)
 fileName = []
 else:
 fileName.append(cmd)

(Which is copy-pasted from the if readingFileName case, with some modifications).

Then, we're going to replace

elif cmd == "0":
 readingFileName = True

with

elif cmd == "0":
 parser_stack.append(read_filename)

and we can remove the if readingFileName: case, because that's now handled by another parser.

I've given some other stuff the same handling.

Continue from here.

import string, sys, random, time, codecs
import functools
import operator
INT_BINOPS = {
 "a": operator.add,
 "s": operator.sub,
 "m": operator.mul,
 "d": operator.truediv,
}
INPLACE_UNARYOPS = {
 "+": functools.partial(operator.add, 1),
 "-": functools.partial(operator.add, -1),
 "/": functools.partial(operator.add, 10),
 "\\": functools.partial(operator.add, -10), # can't use .sub here
 '"': functools.partial(operator.add, 100),
 "'": functools.partial(operator.add, -100),
 "n": int,
 "f": float,
 "%": ord,
 "r": lambda v: codecs.encode(str(v), 'rot_13'),
}
FUNCS = {
 "t": lambda: str(time.ctime()),
 "#": lambda: 0,
 "i": lambda: input(">> "),
}
POSITION_ACTIONS = {
 "$": lambda _: 0,
 ">": functools.partial(operator.add, 1),
 "<": functools.partial(operator.add, -1),
 "{": functools.partial(operator.add, 10),
 "}": functools.partial(operator.add, -10),
 "-": functools.partial(operator.add, 100),
 "_": functools.partial(operator.add, -100),
}
tape = [0] * 25500
funcs = {}
variables = {}
readingStr = False
readingLoopAmount = False
readingLoopCode = False
readingRand = False
readingRand2 = False
readingFName = False
readingFCode = False
appendToFront = False
appendToBack = False
loopInf = False
loopRand = False
string = False
isChar = False
fileName = []
tempText = []
tempName = []
fName = []
fCode = []
text = []
rand = []
rand2 = []
loopCode = []
loopAmount = []
selected = 0
def read(cmd):
 if isinstance(cmd, str):
 cmd = cmd.replace("!K", "1000")
 cmd = cmd.replace("!H", "100")
 for token in cmd:
 parse(token)
def _parse(cmd):
 # Sorry for all these globals...
 global tape
 global funcs
 global variables
 global readingStr
 global readingLoopAmount
 global readingLoopCode
 global readingRand
 global readingRand2
 global readingFName
 global readingFCode
 global appendToFront
 global appendToBack
 global loopInf
 global loopRand
 global vName, vText
 global fileName
 global string
 global isChar
 global tempName
 global tempText
 global fName
 global fCode
 global text
 global rand
 global rand2
 global loopCode
 global loopAmount
 global selected
 if readingFName == True:
 if cmd == "|":
 readingFName = False
 readingFCode = True
 else:
 fName.append(cmd)
 elif readingFCode == True:
 if cmd == "`":
 readingFCode = False
 name = ''.join(fName)
 code = ''.join(fCode)
 funcs[name] = code
 fName = []
 fCode = []
 else:
 fCode.append(cmd)
 elif readingRand == True:
 if cmd == "|":
 readingRand = False
 else:
 rand.append(cmd)
 elif readingRand2 == True:
 if cmd == "|":
 readingRand2 = False
 else:
 rand2.append(cmd)
 elif string == True:
 if appendToFront == True:
 if cmd == "~":
 tape[selected] = str(tape[selected]) + ''.join(tempText)
 tempText = []
 appendToFront = False
 elif cmd == "$":
 tape[selected] = str(tape[selected]) + str(tape[selected-1])
 appendToFront = False
 tempText = []
 else:
 tempText.append(cmd)
 elif appendToBack == True:
 if cmd == "~":
 tape[selected] = ''.join(tempText) + str(tape[selected])
 tempText = []
 appendToBack = False
 elif cmd == "$":
 tape[selected] = str(tape[selected-1]) + str(tape[selected])
 appendToFront = False
 tempText = []
 else:
 tempText.append(cmd)
 elif cmd == "r":
 tape[selected] = tape[selected].reverse()
 elif cmd == "u":
 tape[selected] = tape[selected].upper()
 elif cmd == "l":
 tape[selected] = tape[selected].lower()
 elif cmd == "a":
 appendToFront = True
 elif cmd == "b":
 appendToBack = True
 elif cmd == ".":
 string = False
 elif readingLoopAmount == True:
 if cmd == "|":
 readingLoopAmount = False
 readingLoopCode = True
 elif cmd == "i":
 loopInf = True
 elif cmd == "r":
 loopRand = True
 else:
 loopAmount.append(cmd)
 elif readingLoopCode == True:
 if cmd == "]":
 readingLoopCode = False
 if loopInf == True:
 while 1:
 read(loopCode)
 if loopRand == True:
 if rand and rand2 == []:
 for i in range(0, random.randint(0, 100)):
 read(loopCode)
 else:
 if rand2 == []:
 for i in range(0, random.randint(0, int(''.join(rand)))):
 read(loopCode)
 elif rand == []:
 for i in range(0, random.randint(int(''.join(rand2)), 100)):
 read(loopCode)
 else:
 for i in range(0, random.randint(int(''.join(rand2)), int(''.join(rand)))):
 read(loopCode)
 else:
 for i in range(0, int(''.join(loopAmount))):
 read(loopCode)
 loopCode = []
 loopAmount = []
 else:
 loopCode.append(cmd)
 elif readingStr == True:
 if cmd == "~":
 readingStr = False
 text = ''.join(text).replace("μ", "")
 tape[selected] = text
 text = []
 else:
 text.append(cmd)
 elif cmd == "*":
 print(selected)
 elif cmd == "^":
 print(tape[selected])
 elif cmd == "!":
 if isinstance(tape[selected], str):
 print(tape[selected])
 else:
 print(chr(tape[selected]))
 elif cmd in FUNCS:
 tape[selected] = FUNCS[cmd]()
 elif cmd in INPLACE_UNARYOPS:
 op = INPLACE_UNARYOPS[cmd]
 tape[selected] = op(tape[selected])
 elif cmd in INT_BINOPS:
 op = INT_BINOPS[cmd]
 tape[selected] = op(int(tape[selected]), int(tape[selected + 1]))
 elif cmd in POSITION_ACTIONS:
 selected = POSITION_ACTIONS[cmd](selected)
 elif cmd == "(":
 readingNum = True
 elif cmd == "z":
 tape[selected] = tape[selected+1]
 elif cmd == "x":
 tape[selected] = tape[selected-1]
 elif cmd == "μ":
 readingStr = True
 elif cmd == "[":
 readingLoopAmount = True
 elif cmd == "p":
 return
 elif cmd == ".":
 exit
 elif cmd == "&":
 string = True
 elif cmd == "→":
 if rand != []:
 rand = []
 readingRand = True
 elif cmd == "←":
 if rand2 != []:
 rand2 = []
 readingRand2 = True
 elif cmd == " ̈":
 time.sleep(1)
 elif cmd == "@":
 readingFName = True
 elif cmd == "=":
 parser_stack.append(read_name)
 elif cmd == "¤":
 parser_stack.append(read_vname)
 elif cmd == ";":
 parser_stack.append(read_vname2)
 elif cmd == "0":
 parser_stack.append(read_filename)
parser_stack = [_parse]
def read_name(cmd):
 global tempName
 if cmd == ".":
 parser_stack.pop()
 name = ''.join(tempName)
 read(funcs[name])
 tempName = []
 else:
 tempName.append(cmd)
def read_vtext(cmd):
 global vName, vText
 if cmd == "]":
 parser_stack.pop()
 name = ''.join(vName)
 val = ''.join(vText)
 variables[name] = val
 vName = []
 vText = []
 else:
 vText.append(cmd)
def read_vname(cmd):
 if cmd == "|":
 parser_stack.pop()
 parser_stack.append(read_vtext)
 else:
 vName.append(cmd)
def read_vname2(cmd):
 global vName2
 if cmd == ".":
 parser_stack.pop()
 tape[selected] = variables[''.join(vName2)]
 vName2 = []
 else:
 vName2.append(cmd)
def read_filename(cmd):
 global fileName
 if cmd == "]":
 parser_stack.pop()
 f = open(''.join(fileName), 'r')
 code = f.read()
 f.close()
 read(code)
 fileName = []
 else:
 fileName.append(cmd)
def parse(token):
 return parser_stack[-1](token)
while 1:
 read(input("> "))

Conclusion

I hope I have given you some ideas on how to improve the code even further. I hope it makes sense to you.

I have also ignored a lot of stuff for now (PEP8, globals, etc). If you want you can continue on the path I've shown for a while, and when you see nothing left where you have an idea for improvement, feel free to ask another question for the resulting code. Hopefully it'll be split up enough that you can ask a more specific question.

• Sjoerd Job Postmus: Just don't edit the code in the question (adding usage examples is good though! Thank you!)
• Sjoerd Job Postmus: @m654: I've updated the review with some more, but now I really need to stop tweaking it, because I also have other responsibilities.
• m654: Thanks for the tips! The code looks much better now, and I'm pretty sure it works better as well.
• Sjoerd Job Postmus: I haven't fully tested it. I checked github, it could use automated tests so that you can be more confident in changing the code without breaking functionality.