Grammar

This section describes the grammar of the Horse64 programming language.

Overview

Horse64's grammar is inspired by the Go, Lua, and Python programming languages. It's meant to be verbose enough to be beginner-friendly while still minimal:

func main {
    print("Hello World!")
}

Here's an overview of the basic differences and properties of Horse64's grammar compared to other programming languages:

No line terminators

In some other languages like the C programming language, statements always end with some statement terminating character like a ; at the end, others like the Python programming language have a statement terminating character for at least optional use. This is not the case in Horse64, statements just end where they naturally end, and there is no optional character to end them more explicitly.

No significant whitespace

In some other languages like the Python programming language, indent via space or tabulator characters or line breaks play a role in where statements start or end. This is usually called "significant whitespace".

Horse64 doesn't have such significant whitespace, all code can technically be written with whatever indent or even in one long line. The only exception are comments that begin with # and always end at the next line break.

Statement start restriction

A statement can't ever begin with some specific items:

• ( or [ opening enclosing marks are forbidden, while a { opening brace is allowed,

• a new operator is forbidden,

• an inline if is forbidden, while a standalone if statement start is allowed.

All these are forbidden to avoid ambiguity given the grammar's lack of significant whitespace. If you use them anyway, expect to get yelled at by horsec.

Pitfall of return statements that aren't at block end

A return statement may have an expression following to be returned but it's optional. This can lead to seeming ambiguity, which can be easily avoided with this advice:

Advice: You shouldn't put a return statement anywhere but right before the closing } brace of a code block.

An example follows where ignoring this advice is confusing:

func main {
    return

    # ...not heeding above advice, this is an example of not ending
    # the block after a `return`, but instead adding another call:
    call_my_func()

    # This is misleading, since here's what the compiler sees:
    #   return call_my_func()
}

Formal listing

For the formal rules of the grammar, go here for a listing.

Operators

Find an operator listing here.