Basic Syntax

// is used to add comments.
Use of semicolons (;) is not required.

If you are calling the Run(code) block from a text block. Make sure there are no comments, since anything in a text block gets inlined.

All Java operators are supported (except a few bitwise operarors).

Datatypes

All of the data types are interoperable with App Inventor. Bool, Int, Char, Float, Double, Any, Nil, List, Dict are the supported types.

An example of few:

print(
    "Hello, World!", // a String
    'A',             // a Char
    true,            // a Bool
    123,             // an Int
    12.3,            // a Float
    3.14D,           // a Double
    makeList("App", "Inventor") // a List
    // a Dict
    makeDict(
        "India": "Delhi",
        "USA": "Washington DC"
    )
)

This outputs the following:

Hello, World!
A 
true
123
12.3
3.14
["App", "Inventor"]
{"India":"Delhi", "USA": "Washington DC"}

Conditional Expressions

let x = 5
let y = 8
 
if (x > y) {
  print("X is greater")
} else if (x == y) {
  print("Both are equal!")
} else {
  print("Y is greater")
}

You may use if not just for flow control, but also as an expression:

let x = 5
let y = 8
 
println(if (x > y) "X is greater" else "Y is greater")

For loop

let places = arrayOf("India", "Japan", "Germany")
for (place in places) {
  print(place)
}

or the classical way:

let places = arrayOf("India", "Japan", "Germany")
for (var i = 0; i < len(places); i++) {
  print(places[i])
}

Until loop

let places = arrayOf("India", "Japan", "Germany")
var index = 0
until (index < len(places)) {
  print("Item at index " + index + " is " + places[index])
  index++
}

Special loop

It's one of the special features offered by Eia!

Iterating backwards from 5 to 1:

each (x: 5 to 1) {
  print(x)
}

Iteration from 2 to 10 by increment of 2:

each (y: 2 to 10 by 2) {
  print(x)
}

Type checks and casting

Like Kotlin, the is checks if an expression belongs to a certain type.

let a = "Meow!"
println(a is String)            // true
println("Meow" + 8 is Int)      // false```

To cast values, for example from Any to Int, we use the cast operator :: followed by a type:

// casting from Any to String
let name: Any = "Meow"
let reName: String = name::String

Functions

Eia functions are declared using the fun keyword:

fun square(x: Int): Int {
  return x * x
}

then to call a function:

let squared = square(5)

Parameters

Parameters are defined in the format name: Type and are seperated using commas:

fun sayMeow(n: Int) {
  print("Meow ".repeat(n))
}

Introduction App Inventor Interoperability