SherLang

SherLang is a minimal and lightweight LISP-like programming language implemented in C. The language has it's own handwritten interpreter.

Features

SherLang supports the following features:

• Data Types: Integer, Floating Point, Boolean, Char, String
• Builtin Data Structures: List (Ofcourse, its a LISP :p)
• Polish Arithmetic Notation
• Ordering and Logical Operations: >, <, >=, <=, !=, &&, ||, !
• Functions, Recursive Functions, and Lamba Functions
• Builtin Functions: head, tail, join, len, list, cons, def, put, lambda, load, print, error
• A Standard Library
• Command Line Arguments
• Load SherLang code from a .slang File

Potential Improvements

• Add support for user defined types (e.g. Structs)
• Add OS interaction through system calls
• Improve variable look-ups by using a Hash Table
• Implement a Garbage Collector
• Introduce Static Typing

The language is purposefully kept simple and lightweight. The implemented constructs are chosen carefully such that these constructs can be easily used to implement any new complex feature.

Documentation and Usage

# Defining variables 

SherLang> def {x} 100 # declare a single variable
ok

SherLang> def {y z} 10 20 # declare multiple variables 
ok

SherLang> def {x} "Thanks for using SherLang" # declare a string
ok

SherLang> def {my_list} {1 2 3 4} # declare a list 
ok

# Arithmetic 

SherLang> + 1 (* 7 5) 3
39.00

SherLang> def {x y} 10 20 
ok 

SherLang> - x 
-10.00 

SherLang> % 20 (/ x (+ x y))
0.00 

# Builtin Functions

SherLang> list 1 2 3 4
{1.00 2.00 3.00 4.00}

SherLang> eval {head (list 1 2 3 4)}
{1.00}

SherLang> tail {tail tail tail} 
{tail tail}

SherLang> eval (head {(+ 1 2) (+ 10 20)})
3.00

SherLang> (eval (head {+ - + - * /})) 10 20 
30.00

SherLang> head {1 2 3} {4 5 6}
Error: Function 'head' passed incorrect number of arguments. Got 2, Expected 1.

SherLang> error "This is an error!"
Error: This is an error!

SherLang> len {1 2 3 4} 
4.00 
SherLang> len ""
0.0

SherLang> join {1 2 3 4} {5 6 7 8} {9 10 11 12}
{1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00}

SherLang> join "This" "is" "SherLang"
"ThisisSherLang"

SherLang> cons 2 {1 2 3}
{2.00 1.00 2.00 3.00}

# Defining Functions 

SherLang> fun {add-together x y} {+ x y} 
ok 

SherLang> add-together 10 20 
30.00 

SherLang> (fun {my_len l} {  if (== l {})    {0}    {+ 1 (my_len (tail l))}})
ok 

SherLang> my_len {1 2 3 4 5}
5.00 

SherLang> (fun {reverse l} {  if (== l {})    {{}}    {join (reverse (tail l)) (head l)}}) 
ok 

SherLang> reverse {1 2 3 4 5}
{5.00 4.00 3.00 2.00 1.00}

More useful functions are defined in the Standard Library.

Building

To build and run the project locally, you can follow the following steps:

1. Clone the repository:

https://github.com/saadsheralam/SherLang.git

2. If you do not have gcc (compiler for C) installed, install it by following these instructions.

3. Navigate to the cloned directory.

4. Run the following command to compile the project and link the lreadline library:

gcc parsing.c -o parsing -lreadline

6. Run the project and write your first program in SherLang:

./parsing 

Contributing

Feel free to create a new issue in case you find a bug/want to have a feature added. Proper PRs are welcome.