Lainoa

Built following the https://interpreterbook.com.

I never got far enough in college to the point where I could take the compilers subject, and that's been an itch I've always wanted to scratch. So this is me scratching that itch!

Lainoa is an interpreted language writen in go. It's pretty slow, doesn't have a lot of features, and you shouldn't be using it for anything sane. It's here for educational purposes, and I had a blast 🎉 building it.

Ah, lainoa stands for cloud in Euskera.

Installing and running

Running locally

You'll need golang installed.

Install it:

make install

If you don't want to install it, you can also build the binary to bin/lainoa:

make build

Run a file

# examples/hello_world.ln

let name = "World"

puts("Hello " + name + "!")

> lainoa run examples/hello_world.ln
Hello World!

Run the REPL:

lainoa repl
Hello uesteibar! This is the Lainoa programming language

Go ahead and type some stuff!
⛅️ >>

or with docker

> docker run -it uesteibar/lainoa repl

Features

Lainoa is as simple as a programming language can get.

You have numbers and can do fun math with them:

let one = 1
let two = 2

let five = one + two * 2

Strings are there too:

let name = "Unai"
let last_name = "Esteibar"

let full_name = name + " " + last_name # => "Unai Esteibar"

puts(full_name) # prints Unai Esteibar

And of course booleans and boolean operations:

let lainoa_is_cool = true
let should_i_use_it = false

15 > 10
15 < 10
15 == 10
15 != 10

You can declare functions and pass them around:

let result = 0

let add = fun(a) {
  let number = a

  return fun(b) {
    return number + b
  }
}

let addFive = add(5)

result = addFive(10)

Functions in lainoa are automatically curried when called with less arguments than expected:

let greet = fun(greeting, name) {
  puts(greeting + ", " + name + "!")
}

let hello_greeter = greet("Curried hello")

hello_greeter("Lainoa") # => Curried hello, Lainoa

There's also conditionals of course, otherwise life would be pretty boring:

let status = fun(age) {
  if (age < 18) {
    "little-adult"
  } else {
    "adult"
  }
}

status(21) # => "adult"
status(17) # => "little-adult"

Arrays, because otherwise how would you build a ToDo app? (see this example for a more complex showcase of arrays).

let shopping_list = [
  "milk",
  "cereals",
  "bread"
]

puts(shopping_list[0]) # => "milk"
puts(shopping_list[1]) # => "cereals"
puts(shopping_list[2]) # => "bread"
puts(shopping_list[3]) # => nil

shopping_list = push(shopping_list, "chocolate")
puts(shopping_list[3]) # => "chocolate"

Oh, you can use ; if you want to do things inline, but they're not mandatory otherwise:

let a = 1; a = a + 2;

For funky cases, there's nil:

let a = if (false) { "never" }

puts(a) # => nil

uesteibar / lainoa