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Syntax

Introduction

StarShip uses a functional syntax and only has a few patterns. This makes the syntax easy to learn and parse but might need some adjusting when coming from a language like Swift or Python.

Function definitions

Functions are the most important and common pattern in StarShip. You define a function by giving it a name, followed by two double points (::). Then, you define the data types of the arguments you expect. These need to be separated by an ampersand (&). These arguments will be available as arg1, arg2 and so on. This means the value of the first argument will be available as arg1.

After defining the arguments, you'll need to add an arrow (->) to indicate the following type is the data type you'll return. Right now, every function has to return and can only have one return type.

A function definition will have to be ended with the keyword end

Here is an example of a function definition:

functionName :: String, Bool -> String
    -- code
    -- the first argument (string) is available as arg1
end

Return

Return is written as return. After the keyword, you can either insert an absolute value or reference a variable.

Here is an example of returning an absolute value …

return "hello world"

… and here one of returning a variable

return variableName

Comments

If you want to document your code, you'll need comments. A comment starts with two hyphens (--). The comment spans to the end of the line.

Here is an example of some comments:

-- comment
code -- comment

Variable definitions

If a variable is not yet defined, you can define it with an absolute value or by calling a function. Since you can't call functions without assigning the return value to a variable, you'll define lots of variables. This also helps to document the progress of a program. When defining a variable with an absolute value, use this syntax:

let variableName = 42

Here the keyword is let. It lets the interpreter know, you want to define a new variable. If you want to call a function to define a variable, you put the function name directly after the equals sign. After the name, you list all arguments. These shouldn't be separated by an ampersand.

Here is an example:

let variableName = functionName "hello" "world"

If you want to reassign a variable, you can omit the let keyword. The data type of new value will have to match the one of the original value. Right now, you can't use the value of a variable when redefining it. For example:

variableName = inc variableName -- won't work

Basic data types

Right now, StarShip has three data types:

  • Strings can be written in quotes ("String value")
  • Numbers can be written as numbers (42)
  • Bools have the values True and False

That's it!

StarShip is a pretty simplistic language. It doesn't have many features, but in combination with the standard library, it can do some pretty cool stuff. Install the CLI, and give it a try!