Introduction

This book is the main documentation for the Orn programming language.

Note

For bugs or missing content in this book please open an issue in the GitHub repo.

Warning

Orn is being designed and developed. Some of the syntax in this book may not be implemented yet.

What is Orn?

Orn is a systems language where every type is a range. Instead of choosing between int, u8 or bool, a value is described by the integers it can hold, written lo..hi with both ends inclusive.

age : 0..150 = 30;

The compiler keeps two ranges for every value:

• The declared range fixes how the value is stored. It never changes.
• The known range is what the compiler can prove at each point of the program. Comparisons make it smaller.

classify :: (i: 0..1000) 0..2 {
    if i < 10 {
        // known range of i: 0..9
        0
    } else if i < 100 {
        // known range of i: 10..99
        1
    } else {
        // known range of i: 100..1000
        2
    }
};

Types are aliases

The usual type names are ordinary constant bindings in the standard library:

u8   :: 0..255;
i32  :: -2147483648..2147483647;
bool :: 0..1;

u8 and 0..255 are the same thing. A value can be passed wherever the expected range contains its own.

No silent overflow

Arithmetic follows the ranges of its operands. Adding two u8 gives 0..510, and storing that in a u8 is a compile error. Wrapping or saturating has to be asked for explicitly.

When a value comes from outside and its range is unknown, in checks it at runtime and narrows it:

age :: (n: -32768..32767) 0..150 {
    n in 0..150 else { ret 0; }
};

Limits

Ranges are checked with interval arithmetic, which treats operands as independent. Some correct programs are rejected: x * x with x : -3..3 is -9..9, not 0..9. The examples/errors folder in the repository collects these cases.