Post History

Adding support on mathematical expressions

[MarkFuncs](https://github.com/JoyrenceMatthewAgas/MarkFuncs/) has really gotten huge progress, at least in my eyes, and now, I want to make math possible in the language.

# Background

**MarkFuncs** is a programming language that I have been working on for a while, which is basically a golflang that works like an object-oriented proglang (the summary for the final product). Currently, the language doesn't have a site to run the language, but it does have an interpreter that can run in [TIO](https://tio.run/#python3). Just copy this code into the Code section, then write a program on the Input section:
```python
from ast import arg
from inspect import signature

BAD_RESULT = "err"

def bottles_of_beer(num):
	for i in range(num, 0, -1):
		if i == 1:
			if num == 1:
				print(f"1 bottle of beer on the wall. 1 bottle of beer.\nLet it be to sit in peace. {num} bottle of beer on the wall.")
			else:
				print(f"1 bottle of beer on the wall. 1 bottle of beer.\nGo to the store and buy some more. {num} bottles of beer on the wall.")
		elif i == 2:
			print(f"{i} bottles of beer on the wall. {i} bottles of beer.\nTake one down and pass it around. {i - 1} bottle of beer on the wall.\n")
		else:
			print(f"{i} bottles of beer on the wall. {i} bottles of beer.\nTake one down and pass it around. {i - 1} bottles of beer on the wall.\n")

def str_replicator(str, num):
	for chr in str:
		print(end = chr * num)

functions = {
	"bottle": bottles_of_beer,
	"repl": str_replicator
}

variables = {}

"""
Helper method
returns (string, new index)
"""
def getString(code, i):
	assert(code[i] == '"')
	i += 1
	str = ""
	while code[i] != '"':
		str += code[i]
		i += 1
	i += 1
	return str, i

def getNum(code, i):
	assert(code[i].isdigit() or code[i] == '.')
	float_check = 0
	num = ""
	while code[i].isdigit() or code[i] == '.':
		if code[i] == '.':
			float_check += 1
		num += code[i]; i += 1
		if float_check > 1:
			print("Invalid syntax → Reuse of decimal points", file = sys.stderr)
			return BAD_RESULT, i
	if float_check == 0:
		return int(num), i
	else:
		return float(num), i

def program(code):
	i = 0
	while i < len(code):
		if code[i] == '→':
			if code[i+1] == '"':
				i += 2
				str = ""
				while code[i] != '"':
					str += code[i]; i += 1
				print(str)
				i += 1
			elif code[i+1].isdigit():
				i += 1
				equation = ""
				while code[i] != ';':
					equation += code[i]; i += 1
				i += 1
			elif code[i+1].isalpha():
				i += 1
				var = ""
				while code[i] != ';':
					var += code[i]; i += 1
				print(variables[var])
				i += 1
			else:
				print(f"Invalid syntax → {code[i]} is not a variable", file = sys.stderr)
		elif code[i].isalpha():
			funcname = ""
			while code[i].isalpha() or code[i].isdigit():
				funcname += code[i]; i += 1
			if code[i] == '(':
				args = []
				i += 1
				while (code[i] != ')'):
					if (code[i] == '"'):
						arg, i = getString(code, i)
					elif (code[i].isdigit() or code[i] == '.'):
						arg, i = getNum(code, i)
					else:
						print(f"Invalid argument → {code[i]} can't be an argument", file = sys.stderr)
					args.append(arg)
					if (code[i] == ','):
						i += 1
					else:
						assert(code[i] == ')')
				i += 1
				if functions[funcname]:
					func = functions[funcname]
					num_req_args = len(signature(func).parameters)
					if (num_req_args != len(args)):
						print(f"Not enough arguments → {funcname} requires {num_req_args} but only {len(args)} were given", file = sys.stderr)
					else:
						func(*args)
				else:
					print(f"Invalid function → {funcname}() does not exist", file = sys.stderr)
			elif code[i] == '=':
				i += 1
				if (code[i] == '"'):
					val, i = getString(code, i)
				elif (code[i].isdigit() or code[i] == '.'):
					val, i = getNum(code, i)
				i += 1
				variables[funcname] = val
		else:
			print(f"Invalid syntax → Character {code[i]} undefined", file = sys.stderr)

while True:
	try:
		s = input()
		program(s)
	except:
		break
```

An example program you can run is:
```none
var1="Hello, ";
→var1;var2="World!";
→var2;
```

The language is obviously incomplete, and I'm using Q&A so I can add more stuff, not just to rely on the [Discord server](https://discord.gg/wwh8XZ9CWS).

# Main Deal

I currently want to implement the mathematical expressions in programming. There are a few things to deal with:

1. Calculate with integers and floating-point numbers:
```none
→3+5; ` Full program
→     ` Output function
 3+5  ` Add 3 and 5
    ; ` Trigger to start a new line
```
<sup>Backticks are supposed to be the syntax for comments, which will be implemented soon.</sup>

2. Calculate variables:
```none
x=10;y=15;→x+=y; ` Full program
x=10;            ` Assign x with 10
     y=15;       ` Assign y with 15
          →x+=y; ` Output x+y, assign x with sum of x and y
```
3. Access the values of variables in functions
```none
i=100;bottle(i-1); ` Full program
i=100;             ` Assign i with 100
      bottle(i-1); ` Run "N Bottles of Beer" using i+1 (see tutorial for more info)
```

I currently have no idea how to implement this properly, especially with the syntax I have involved:
```
+ plus
- minus
* times
/ divided by
% modulo
^ exponentiate
⊕ XOR

Use GOEMDAS when doing math:
- Grouped equations first
- Functions such as modulo and XOR go first
- Exponents are next
- MD: if multiplication goes first in equation, do all multiplication, same goes for division
- AS: if addition goes first in equation, do all addition, same goes for subtraction
```

So how can I properly implement this system under MarkFuncs syntax?