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The classic Hello World program is the perfect starting point for learning Elara. This example demonstrates the basic structure of an Elara program and how to perform simple output.
1

Basic Hello World

The simplest Elara program that prints output:
def main : IO ()
let main = print "Hello, World!"
What this does:
  • def main : IO () declares the type signature for main as an IO action that returns unit (nothing)
  • let main = print "Hello, World!" defines the main function that prints the string
  • The print function comes from the standard library and outputs text
Expected Output:
Hello, World!
Every Elara program must have a main function of type IO () as the entry point.
2

Using println

You can also use println to automatically add a newline:
import Prelude
import Elara.Prim

def main : IO ()
let main = println "Hello, World!"
Expected Output:
Hello, World!
println is preferred over print in most cases as it adds a newline character automatically.
3

String Concatenation

You can build more complex strings using the ++ operator:
import Prelude
import Elara.Prim
import String

def main : IO ()
let main =
    let name = "Elara"
    let version = "0.1"
    println ("Welcome to " ++ name ++ " v" ++ version ++ "!")
Expected Output:
Welcome to Elara v0.1!
Key Concepts:
  • The ++ operator concatenates strings
  • Local bindings use let expressions
  • The String module provides string utilities
4

Working with Numbers

Converting numbers to strings for display:
import Prelude
import Elara.Prim
import String

def main : IO ()
let main =
    let answer = 42
    println ("The answer is: " ++ toString answer)
Expected Output:
The answer is: 42
Key Concepts:
  • toString converts integers to strings for concatenation
  • Numeric literals are inferred as Int by default

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Next Steps

Now that you understand the basics, explore more advanced examples:

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