This is a simple cli calculator created in Rust. It's a personal project to learn about interpreters. The calculator is a scientific calculator with a limited feature set:
- arithmetic operations:
-,+,*,/and% - trigonometric functions:
cos,sinandtan - other functions:
max,min,floor,ceil,log
Additionally, this calculator allows the definitions of variables with the let keyword.
After running the following commands, you will enter a REPL where you can type in mathematical expressions to be calculated.
git clone https://github.com/somecho/cli-calculator
cd cli-calculator
cargo run
This calculator uses conventional mathematical notation (i.e. infix). For functions, the syntax reads a little bit more like programming languages. The syntax for functions is FUNCTION(ARG) for functions with single arity, FUNCTION(ARG,ARG) for functions with double aritoes and FUNCTION(ARG,ARG,...) for functions with multiple arities.
- Single arity:
cos(3.1415) - Double arity:
pow(2,5.14) - Multiple arity:
min(1,2,3,4,7)
Expressions can be nested. min(cos(max(5,10)),pow(10,2),log(100)) would be a valid expression.
Variables can be defined using the let keyword.
let a = 10
a * 10
=> returns 100
The program follows a simple architecture, first scanning the input string to produce a list of tokens. The tokens then get parsed using recursive descent into an abstract syntax tree, which then finally can be evaluated.