Osklang - A simple programming language

Types

Numbers

Floating point numbers, integers and all basic math operators are available in Osklang:

1 + 2 -- 3
7 - 3 -- 4
6 * 4 -- 24
9 / 2 -- 4.5
7 % 2 -- 1

Strings

Strings are created using ', ", or `:

"Hello World!"
'Foo'
`Bar`
-- These are all valid strings

Strings can be added together using +:

'Foo' + 'Bar' -- 'FooBar'

Strings can also be multiplied by integers:

'Foo' * 5 -- 'FooFooFooFooFoo'

Booleans

Booleans hold either the value of true of false.

Nil

nil is the only type that can only have nil as value. It is also falsy, which means it is coerced to false when used in an if statement or a while loop.

List

A list is a special type that can contain any number of elements of any type. It is created using [ and ]:

[1, 2, 3]
['Foo', 'Bar']
[1, 'Foo', true]

Variables

Variables are dynamically typed, do not need declaration, and are function scoped.

name = 'Bob'
age = 10
isMinor = true

Osklang supports incrementation and decrementation for number variables.

x = 10 -- 10
x += 2 -- 12
x -= 20 -- -8

y = 'Hello'
y += ' World!'
-- y is now 'Hello World!'

Because variables when assigned return their new value, you can chain variable declarations:

x = y = z = 'foo'
print(x, y, z) -- foo foo foo

If statements

The if statement is a series of comparative expression that if evaluated to true execute their code block. If none are executed, the else block executes if present.

if x == 10 do
  ...
elif x <= 20 do
  ...
else
  ...
end

For loops

The for loop must have a start and target expression, and can have an optional step expression. Here are several examples:

for x = 0, 10 do
  print(x)
end
-- Will output: 0 1 2 3 4 5 6 7 8 9

for x = 0, 10, 2 do
  print(x)
end
-- Will output 0 2 4 6 8

The step can also be negative:

for x = 10, 0, -1 do
  print(x)
end
-- Will output 10 9 8 7 6 5 4 3 2 1

Functions

In Osklang, there are two types of functions. The first is the single expression functions:

add = function(a, b) => a + b

They do not require a return statement, as they always return their expression.

The second type is the multiple statement function:

canPass = function(age) do
  if age >= 18 do
    return 'You can pass.'
  else
    return 'You are underage.'
  end
end

Both are not named, but they return a function value that can be stored in a variable. That variable can then be called like so:

x = add(15, 8)

canBobPass = checkAge(x)