? Mellang ?

Mellang, an interpreted programming language

Mellang VSCode Extension

You can download it on https://marketplace.visualstudio.com/items?itemName=Mello.mellang

Mellang can do almost anything that a basic programming language does:

Types

Mellang has the following data types: null, bool, int, str, array, hash,fn and a “strange” float

Type Syntax
null null
bool true false
int 0 24 1654 -10
str "blablabla string here"
array [] [1, 2] [1, 2, 3]
hash {} {"a": 1} {"a": 1, "b": 2}
float 1.6 1.6324 215.16

Variable Bindings

You can use ‘moonvar (var) = (expression)’ or just ‘(var) <- (expression)'

moonvar myVar = 5
anotherVar <- 5 

Arithmetic Expressions

>> myVar > moonvar anotherVar > (myVar + anotherVar) / 2 - 3
12

OwO Operators

moonvar funcOne = fn(x){x *10}

moonvar TEST = fn(x){x * 2}

moonvar ac = OwO 10 ~> funcOne ~> TEST ~> funcOne ~> funcOne ~> funcOne
(10 * 10 * 2 * 10 * 10 * 10)

>> ac
> 200000

moonvar myList = [1,2,3,4,5]

moonvar sumList = fn(list){map(list, TestTWO)}

OwO myList ~> sumList ~> sumList;
>[5,6,7,8,9]

moonvar elixirLike = OwO "Eae Beleza" ~> String_Upcase ~> String_Split;
>[EAE, BELEZA?]


Conditional Expressions

Mellang supports if and else:

>> a > b > c  a) { 99 } else { 100 }
>> c
> 99

>> a > b > c = a) { 99 } else { 100 }
>> c
> 99

Installation

TODO

Usage example

Variable Declaration

moonvar myVariable = 5
moonvar myFunction = fn(x){x + 1}
moonvar myHash = {"name": "myName", "otherName : "randomName"}
moonvar myList = [1,3,4,5, fn(x){x + 1}]

myList[4](5)
> 6

myHash["name"]
>myName

map([1,2,3,4],fn(x){x * 2})
>[2,4,6,8]

sum(map([1,2,3,4],fn(x){x * 2}))
>20

While Loops

Mellang supports only one looping construct, the while loop:

x <- 3
myList  0) {
 myList <- map(myList,fn(x){x * 2}) 
 plsShow(myList) 
 x <- x - 1
}

// [2,4,6,8,10]
// [4,8,12,16,20]
// [8,16,24,32,40]

Functions and Closures

You can define named or anonymous functions, including functions inside functions that reference outer variables (closures).

>> moonvar multiply = fn(x, y) { x * y }
>> multiply(50 / 2, 1 * 2)
50
>> fn(x) { x + 10 }(10)
20
>> moonvar newAdder = fn(x) { fn(y) { x + y } }
>> moonvar addTwo = newAdder(2)
>> addTwo(3)
5
>> moonvar sub = fn(a, b) { a - b }
>> moonvar applyFunc = fn(a, b, func) { func(a, b) }
>> applyFunc(10, 2, sub)
8

Recursive Functions

Monkey also supports recursive functions including recursive functions defined in the scope of another function (self-recursion).

>> moonvar wrapper = fn() { moonvar inner = fn(x) { if (x == 0) { return 2 } else { return inner(x - 1) } } return inner(1) }
>> wrapper()
2


>> fib > fib(35, 0, 1)
9227465

Strings

>> makeGreeter > hello > hello("mellum")
Hello mellum!

Arrays

>> myArray := ["Thorsten", "Ball", 28, fn(x) { x * x }]
>> myArray[0]
Thorsten
>> myArray[4 - 2]
28
>> myArray[3](2)
4

Hashes

>> myHash := {"name": "Jimmy", "age": 72, true: "yes, a boolean", 99: "correct, an integer"}
>> myHash["name"]
Jimmy
>> myHash["age"]
72
>> myHash[true]
yes, a boolean
>> myHash[99]
correct, an integer

Builtin functions

  • len(iterable) Returns the length of the iterable (str, array or hash).
  • first(iterable) Returns the first element of the array.
  • last(iterable) Returns the last element of the array.
  • push(iterable) Add an element to the array.
  • replace(string,element_to_replace,element_to_put) Replace something inside a string.
  • plsShow(element) Print something in the screen.
  • Strcomp(string,string) Compare the pointers of two strings.
  • String_Upcase(string) Upcase an entire string.
  • String_Split(string) Split a string into array

Development setup

After dowloading the Mellang VSCode Extension, you have to create a “.mel” file on the root of the project and specify the filename after running the “main.go”.

Meta

Antonio Mello Babo – @MelloTonio

It was inspired by the monkey language of the book “writing an interpreter in go – thorsten ball”

GitHub

https://github.com/MelloTonio/Mellang