caesium-lang 1.1.0

A simple way to evaluate Boolean Algebra.

Caesium

Caesium is a simple language built to help myself (and others) learn about and understand how Boolean algebra works. To this end, it can evaluate some

Installation

1. Ensure that you have a working version of python3 (If you don't, you can get it from the official site). Any python version >= 3.3.0 should work.
2. Install caesium using pip by running pip install caesium-lang from the command line.
3. Test it out by running the command caesium in your command line.

Usage

Starting the Prompt

You can start the prompt by running caesium. Please note that this route can only work if you follow Step 4 of the Installation guide.

You can also start the prompt by navigating to the root directory of this project and running python3 caesium.py.

Example:

$ caesium
caesium v1.1.0 running on win32.
Press Ctrl+C or type "exit" to quit.
Cs>

If you want to close the interpreter now, skip down here to learn how to.

Expressions

An expression is any valid piece of code which returns a value. Expressions are evaluated right to left unless brackets (()) are used. If brackets are used, they are evaluated from the innermost to the outermost pair.

Values

There are only 2 built-in values: True and False (or 1 and 0 respectively). Caesium is case-insensitive they will work both in upper and lower case.

There is also the random keyword which randomly evaluates to either True or False every time it's used.

Cs> TRUE
True
Cs> False
False
Cs> 0
True
Cs> 1
False
Cs> random
True

Assignment

You can assign a name to a value by putting a valid identifier on the left, a = and finally any valid expression. A valid identifier is any string of Unicode text that is not a keyword in Caesium and does not contain any whitespace characters. Just like in python, assignments can be chained together. Since assignments are expressions, they can be nested within larger expressions.

Cs> foo = True
True
Cs> quux = coco = (True ^ (bar = True)) & False
False

Operators

In caesium (and Boolean algebra in general),there are 2 types of operators, basic operators and derived operators.

Basic Operators

Basic operators, together with the 2 Boolean values, are the building blocks of Boolean algebra. There are only 3 of these basic operators. They are:

1. NOT

NOT takes one value and flips its value. NOT can also be written as !. NOT operations can be tabulated as:

Expression	Result
!True	False
!False	True

2. AND

AND takes 2 arguments and checks if both of them evaluate to True. If they both do, it returns True, otherwise it returns False. AND can also be written as & or &&. AND operations can be tabulated as:

Expression	Result
True AND True	True
True AND False	False
False AND True	False
False AND False	False

3. OR

OR also takes 2 arguments and checks if both of them evaluate to False. If they both do, it returns False, otherwise it returns True. OR can also be written as | or ||. OR operations can be tabulated as:

Expression	Result
`True
`True
`False
`False

Derived Operators

Derived operators, as their name implies, are derived from basic operators. All of them can be rewritten using only the basic operators.

1. XOR

XOR, or eXclusive OR, works just like OR, but both values cannot be True. XOR can also be written as ^. XOR operations can be represented in a table as:

Expression	Result
True ^ True	False
True ^ False	True
False ^ True	True
False ^ False	False

2. NOR

NOR, or Not OR, also works like OR, but it returns the opposite of what OR would. It can also be written as ~. <val_1> ~ <val_2> is just shorthand for !(<val_1> || <val_2>). NOR operations can be represented in a table as:

Expression	Result
True NOR True	False
True NOR False	False
False NOR True	False
False NOR False	True

3. NAND

NAND, or Not AND, works exactly like AND, but it returns the opposite of what AND would. It can also be written as @. <val_1> NAND <val_2> is just shorthand for NOT (<val_1> AND <val_2>). NAND operations can be represented in a table as:

Expression	Result
True @ True	False
True @ False	True
False @ True	True
False @ False	True

Comments

Comments are lines of text meant for other people to read, rather than for the interpreter to run. If a line begins with a # character, the entire line is treated by the interpreter as if it contains nothing.

Errors

When you try to run code which has a mistake (like a missing bracket), the interpreter complains about your code instead of running it. This is an error. An error is basically the interpreter alerting you that there was something wrong with the code and so it can't run it. Once an error is thrown, you will have to fix whatever is wrong with your expression and rerun it.

Examples:

Cs> quux
Undefined name "quux".
Cs> random/  # Meant to say "random"
Invalid syntax: "/".

Exiting

Either pressing Control + C or typing in exit and hitting Enter will cause the interpreter to stop instantly and take you back to the normal shell.

Cs> exit
$

---

TODO

• An internal help mechanism so that you don't have to keep referring to the README.

Development Setup

1. Create a virtualenv.
2. Install the development packages by running pip install -r requirements-dev.txt.
3. Assert everything is working by running pytest tests.py from the project's root dir.

Contributing

1. Crete your feature branch by forking the develop branch.
2. Commit your changes.
3. Push to origin/develop.
4. Open a pull request.

Notes

Just like the element Caesium, this app may break down. In case it does, please contact me or if you wish, you may fix it yourself and submit a pull request.

Meta

• Name: Armani Tallam
• E-Mail: [e-mail]
• GitHub: https://www.github.com/Armani-T (You are literally on it.)

This project is licensed under the BSD 3-Clause License. Please see the license file for more information.