J4 website

Introduction

J4 does away with verbose, unreadable code and replaces it with a readable, understandable coding language that standardizes meaningful, beautiful code. This is made possible with whitespace matching and utilizing syntax that emphasize the flow of information. Along with these leaps forward in code structure, J4 simplifies coding conventions by handling the minutia of memory management and reinventing the outdated and arbitrary rules present in other languages.

J4 pulls inspiration from Swift, ELM, Python, and Lua

Features

• .j4 File Extension
• Whitespace Sensitive
• Easy Array Creation
• Powerful Object Creation
• First Class Functions
• Higher Order Functions
• Static Typing
• Strong Typing

Operators

• Additive: +, -
• Multiplicative: *, /, %
• Exponentiation: ^
• Relational: <, >, >=, <=, =
• Boolean: and, or

Data Types

• Number: 2, 8.0, 3.1415926
• Boolean: true, false
• String: “a”, `“hello world”
• Function: addOne(x)
• Array: [“Martinez”, "Goocher", "Hardy", "Watkins”]
• Object: Color magenta <- new Color(1.0,0.0,1.0), Color halfGray <- new Color(0.5)
• Comments: ~ Single line comment (~ Multi line comment ~)

Example Programs

J4 on the left, Javascript on the right

Variable Declarations

String name <- "j4"                               let name = “j4”;
Number age <- 1                                   let age = 1;
Boolean hasArrows <- true                         let hasArrows = true;

Arithmetic

Number x <- ((4 + 3) * (10 - 1) ^ 2) / 4                 x = ((4 + 3) * Math.pow((10 - 1), 2)) / 4;

If Statements

if i=2                                           if (i===2){
    f(i)                                             f(i);
else if i>5                                      } else if (i>5){
    g(i)                                             g(i);
else                                             } else{
    h(i)                                             h(i);
                                                 }

For Statements

for Number i<-1, i<7, i<-i+1                      for (let i=1; i<7; i++) {
    f(i)                                              f(i);
                                                  }

While Statements

while i<7                                         while (i < 7) {
   f(i)                                               f(i);
                                                  }

Functions

Function twice(f:(Number) -> Number, x:Number) -> Number        var doTwice = (f, x) => {
    return f(f(x))                                                  return f(f(x));
                                                                }
Function addOne(x: Number) -> Number                            function addOne(x){
    return x+1                                                      return x+1;
                                                                }

Concat To increase readibility and learnability, strings do not use the "+" operator instead, the concat function is called to concatenate two or more strings

String s <- concat("Hello ", "World!")                  let s = "Hello" + "World";

Object Declarations

struct Color
  Number red, green, blue <- 0, 0, 0

  init(r: Number, g: Number, b: Number)
    self.red   <- r
    self.green <- g
    self.blue  <- b

  Function getColor(Nothing) -> Number[]
    Number[] rgb <- [self.red, self.green, self.blue]
    return rgb

Color magenta <- new Color(1.0,0.0,1.0)
Color halfGray <- new Color(0.5)

Semantic Analysis

• changedImmutableType : tried to change x from type Number to String.
• isNotAFunction : f is not a function
• isNotAnArray : l is not an array
• isNotAnObject : d is not an object
• doesNotHaveProperty : x does not have property x.property
• invalidBinaryOperands : List and Number cannot be used with +
• invalidUnaryOperand : String cannot be used with ‘not’
• parameterArgumentMismatch : f has signature Number, Array but was called with signature String, Array, Number
• expressionIsNotTypeBoolean : x + 3 is type Number but must be type Boolean
• notDeclared : tried to use x before it was declared
• notInitialized : x is not given a value
• notDeclared : x has not been declared
• alreadyDeclared : x has already been declared
• returnOutsideFunction : found a return statement outside of a function
• typeMismatch : expected String got Number
• typeDoesNotExist : X y expects object ‘X’ is a type for variable y
• noClassConstructor : did not find a constructor in class C
• invalidAccessType : arr["2"], Cannot access a list using a string, need a number
• arrayIndexOutOfBounds : tried to access an element outside of the bounds of the array