References

What a reference is

The ^ operator, written after a variable, creates a reference to that variable. A reference and the variable it points to share the same storage. Write through the reference, and the original variable changes too.

def main() -> Int32
    x: Int32 = 10
    r: Int32 = x^
    print(r)
    r += 5
    print(r)
    print(x)
    return 0

Changing r changed x. They are the same slot now.

How to create one

Write a variable's name followed by ^, and assign it to a new variable of the same type:

r: Int32 = x^

The reference takes on the value the variable holds at that moment, and stays linked to it from then on.

Rules

• A reference must point at a variable. x^ where x is a variable is fine. 5^ or (a + b)^ is a compile error.
• The reference has the same type as the variable it points at.
• Chains of references are fine. You can take a reference to a reference.
• Cycles are not allowed.

Why you'd use one

References let you update a variable through another name, and plain = works through them too. So while reassignment is available for local variables, ^ is the way to change a variable that lives somewhere else — from a nested call or a shared slot.

Because the reference shares storage, updating it updates the original everywhere it's used. The pointer example in the repo plays with this idea.