Lunarlang

Small programming language made for the code community code jam.

Installation

Everything is available via a nix flake.

Usage

Playground:

lunar playgruond

Run the examples:

lunar exec examples/hello.lun
lunar exec examples/functions.lun

Help

lunar --help

Docs

Comments:

• Any line which stats with # will be ignored

Expressions:

• In lunar lang most things are considered expression. An expression has one, and only one return value.
• A expression can be single line:

1 + 1
# returns 2

• Or multi line:

{
    1 + 1
    2 + 2
} # returns 4

Declaring variables:

• To declare variables use the declare keyword followed by a list of name value pairs:

declare a = 1, b = 2, c = 3

• You can replace declare with const to make all of them immutable:

const a = 1, b = 2, c = 3

• For non constant values the initial value is optional:

declare a, b = 7, c

Asigning to variables:

• Use the = operator:

declare a = 3

a = 4

• Note: you cannot assign to constant variables

Calling functions:

• To call a function write the name of the function followed by a list of arguments delimited by paranthesis:

println('1' 2 1 + 1)

• For readability you can also add commas:

println('1', 2, 1 + 1)

• You can also use the pipe operator:

1 + 1 |> println

# Same as println(1 + 1)

Declaring functions:

• To declare a function, use the fn keyword followed by the list of arguments and a expression

const a = fn (a b c) a + b + c

a(1 2 3) # 6

• The return is an expression so you can add brackets:

const a = fn (a b c) {
    const sum = a + b + c
    sum
}

a (1 2 3) # 6

• You can add commas for readability:

const a = fn (a b) a + b

# Same as
const a = fn (a, b) a + b

Async

In lunar everything looks sync by default but is async under the hood:

For example:

sleep(0.5)
println("a")
sleep(0.5)
println("b")

will wait half a second, print a, wait another half a second and print b.

Running stuff in parallel

You can run stuff in parallel with the parallel function:

For example:

const waitAndPrint = fn (time msg) fn () { sleep(time) msg |> println }

parallel(waitAndPrint(0.5 "a") waitAndPrint(1 "b"))

will print "a" after half a second and "b" after 1 second