A simple way to evaluate Boolean Algebra.
Project description
Caesium
Caesium is a simple language built to help myself (and others) learn about and understand how Boolean algebra works. It does this by providing an interpreter for Boolean algebra.
Installation
- Ensure that you have a working version of python (You can get python3 from the official site if you don't have it or want to upgrade). Any python version >= 3.6.0 is officially supported so it should work. Older versions of python3 will probably work but they are not officially supported so use them at your own risk.
- Install caesium using pip by running
pip install caesium-lang
from the command line. - Test it out by running the command
caesium
in your command line.
Usage
Starting the Prompt
You can start the prompt by typing the word caesium
into your terminal and pressing Enter. The caesium prompt should start and print something out to the screen like so:
$ caesium
caesium version 1.3.1 running on win32.
Press Ctrl+C or type "exit" to quit.
Cs>
If you wish to close the interpreter now, scroll down to the Exiting header or press here to learn how to do that.
Expressions
An expression is any valid code which can be turned into a single value. All valid code is made
up of expressions (except the exit
keyword which exits the prompt).
Expressions are
evaluated right to left by default unless brackets (()
) are used.
Values
There are only 2 built-in values: True
(or 1
) and False
(or 0
). Caesium is
case-insensitive, so it will accept them in upper, lower or even mixed case.
There is also the random
keyword which randomly evaluates to either True
or False
whenever
it is used.
Cs> TRUE
True
Cs> False
False
Cs> tRuE
True
Cs> 0
True
Cs> 1
False
Cs> random
True
Assignment
You can bind a name to a value by putting a valid name, then a =
and any valid expression. A valid name is made up of any number of alphanumeric characters and underscores.Valid names also cannot be keywords. Assignments can be chained together to define more than one variable at once. Since assignments are expressions, they can be nested within larger expressions. I wouldn't recommend this though, it makes the line quite unreadable.
Cs> foo = True
True
Cs> quux = coco = (True ^ (bar = True)) & False
False
Operators
In Boolean algebra,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. Without them, Boolean algebra simply wouldn't exist. There are only 3 basic operators:
1. NOT
not
takes a value and flips its value. It can also be written as !
. Its operations can be summarised as:
Expression | Result |
---|---|
not True |
False |
not False |
True |
2. AND
and
takes 2 arguments and checks if both of them evaluate to True
. and
can also be written as &
or &&
. and
operations can be summarised 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
. or
can also be written as |
or ||
. or
operations can be summarised as:
Expression | Result |
---|---|
True or True |
True |
True or False |
True |
False or True |
True |
False or False |
False |
Derived Operators
Derived operators are called "derived" because they are derived from the basic operators (they can be re-written as basic operators). Since we ,as programmers, are too lazy to write them out in full, we made them as a kind of shorthand.
1. XOR
xor
(eXclusive OR) works just like or
, but where both values cannot be True
. xor
can also be written as ^
. xor
operations can be represented in a table as:
Expression | Result |
---|---|
True xor True |
False |
True xor False |
True |
False xor True |
True |
False xor False |
False |
2. NOR
nor
(Not OR) also works just like or
, but it negates what or
returns. It can also
be written as ~
.nandnor
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
(Not AND) works exactly like and
, but it negates what and
returns. It can also be
written as @
. nand
operations can be represented in a table as:
Expression | Result |
---|---|
True nand True |
False |
True nand False |
True |
False nand True |
True |
False nand False |
True |
Help
Rather than having to refer to the README every single time you don't remember what an operator does, caesium comes with the help
command. It is used to print out a line of explanation about the operator passed to it.
It is useed by typing help
then the operator in question like so:
Cs> help or
or checks if at least one value is true.
Comments
Comments are lines of text meant for other people to read, rather than for the interpreter to run. Everything that comes after a #
character is treated by the interpreter as if it is not there. So for example, if a line starts with a #
, the entire line will be treated as if it were blank.
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 then rerun it.
Examples:
Cs> quux
Error: Undefined name "quux".
Cs> random/ # Here I'm supposed to write "random"
Error: 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
$
Development Setup
- Install development packages by running
pip install -r requirements-dev.txt
inside a fresh virtualenv (for this project, we use the.venv
folder). - Assert everything is working by running
pytest tests.py
from the project's root dir.
Contributing
- Create your feature branch by forking the
develop
branch. - Commit your changes.
- Push to
origin/develop
. - 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 want to, fix it yourself.
Meta
- Name: Armani Tallam
- E-Mail: armanitallam@gmail.com
- GitHub: https://www.github.com/Armani-T
This project is licensed under the BSD 3-Clause License. Please see the license file for more information.
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