Jenny

A very simple Scheme-like interpreted language. 👨🏻‍💻

Installation

npm install jenny -g

Demo

About

A lot about jenny is inspired buy scheme. currently scheme executes on Javascript VM, i.e it uses Nodejs to run.

Language Features -

• Data Types
• Declarations & Updating Identifiers
• Code Comments
• Arthmatic Operators
• Funtions
• Block Scope
• Lambda Functions
• Control Flow Statements

  • if statement
  • switch statement

• Iteration Controls

  • while loop
  • For Loop

• Recurssion

Data Types

Language currently supports three primitive data types.

1. Number
2. String
3. Boolean

Declaring and initializing data

Every statement in the language is an expression. every time you declare something explicitly returns the value.

Declaration :

(var name "Jordan") //Declaring name ans setting to "Jordan"
(var age 25) 

/* Updating indentifier */

(set name "King")
(set age 30)

Code Comments

Use /* code comment */ For both single line and multi line comments.

Arthmatic Operators

The language supports left associativity. So the operator is on the left and operands are space separated.

/* addition */

(+ 10 10)   /* Outputs 20 */
(* 10 10)   /* Outputs 100 */
(/ 10 10)   /* Outputs 1 */

Nested Operations : /* nested */

var sum (+ 1 (+ 10 10))

print sum // outputs 21

Functions

Function declarations are done using func keyword.

(begin
    func addNumbers (a b) (
        (+ a b)
    )

    (addNumbers 1 1)
)

Lambda Functions

Lambda functions are used pass functions as callbacks. lambda keyword is used to declare the lambda function .

(begin 
    (func onClick (callback)
        (begin 
            (var x 10)
            (var y 20)
            (callback (+ x y)) 
        )
    )
    (onClick (lambda (data) (* data 10)))
)

Block Scope

begin keyword is used to define a block and all variable declarations are scoped to block. Inner blocks have access to outer blocks.

(begin
    (var name "Jordan") 

    (begin

        (var newName "Jim")
        /* Scoped only to the current block */

        (print name)
        (print newName)
    )
)

Control Flow Statements

If statement

(begin 
    (var age 18)

    (if (< age 18) 
        ("Under 18") /* if the condition is met this block is executed */
        ("Adult") /*  this is the else part*/
    )

)

Switch Case Statement

/* Begin statement */
(begin 
    (var x 100)

    (switch 
        ((= x 100) 1)
        ((= x 200) 2)
        (else 500)
    )
)

Iteration Controls

While statement

(begin
    (var result 0) 
    (while (< result 10)
        (set result (+ result 1))
    )
)

For Loop

(<for keyword> (<initialization block>) (<bail out condition>) (<increment block>) (<block>))

(begin
    (var result 1)
    (for (var x 1) (< x 10) (set x (+ x 1))
        (begin 
            (set result (+ result x))
        )
    )
)

Recurssion

(begin 
    (func factorial (input)
        (if (= input 1)
            1
            (* input (factorial (- input 1)))
        )
    )   
    (factorial 5)
)

Special thanks to Srinivas Pulagam & Dmitry Soshnikov for all the mentoring and help.