Ownership and Memory

Placeholder: Brief overview. For detailed specifications, see the ownership and borrowing specs.

Core Principles

Rask’s memory model is built on three principles:

1. Single ownership - Every value has one owner
2. Move semantics - Assigning/passing transfers ownership
3. Scoped borrowing - Temporary access that can’t escape

Ownership Transfer

const s1 = string.new("hello")
const s2 = s1              // s1 moved to s2, s1 is now invalid
// println(s1)             // Error: s1 has been moved

Borrowing

Borrowing gives temporary access without transferring ownership:

func print_len(s: string) {
    println(s.len())       // Borrows s
}

const text = string.new("hello")
print_len(text)            // text is borrowed
println(text)              // text still valid here

The borrow lasts only for the function call - text remains valid after.

Copy vs Move

Small types (≤16 bytes) copy implicitly:

const x: i32 = 42
const y = x                // Copy (i32 is small)
println(x)                 // x still valid

Large types move:

const v1 = Vec.new()
const v2 = v1              // Move (Vec is large)
// println(v1.len())       // Error: v1 has been moved

To keep access, explicitly clone:

const v1 = Vec.new()
const v2 = v1.clone()      // Explicit copy
println(v1.len())          // Both valid
println(v2.len())

Why No Storable References?

Rask doesn’t allow storing references in structs or returning them. This eliminates lifetime annotations:

• ✗ No 'a lifetime parameters
• ✗ No borrow checker fights
• ✓ Simple ownership rules
• ✓ Predictable behavior

For graphs and cycles, use handles instead of references.

Next Steps

• Collections and Handles
• Formal ownership spec
• Formal borrowing spec