Variables And Mutability

Let Bindings

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Variables are bound in Sage using the let keyword. You can optionally include the type of the variable to be typechecked against.

// Create a variable named a, with the value 5
let a = 5;
let b = {x=5, y=6};
let c: (Int, Int, Int) = (1, 2, 3); // Optionally include the type

println(a);
println(b);
println(c);

Mutability

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You can make a variable as mutable with the mut keyword. If you try to assign to a variable that isn’t mutable, the compiler will yell at you!

let mut a = 5;
println(a);
a = 6;
println(a);

Destructured Let Bindings

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In many instances, users want to be able to decompose the attributes of structures or tuples into variables.

let (a, {mut x, y}) = (1, {x=5, y=6});
println(a, ", ", x, ", ", y);
x = 999;
println(a, ", ", x, ", ", y);

Variables And Scope

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Variables are not captured by functions – functions mainly act as procedures. Additionally, variables may not be referenced before their definition.

println(a);
let a = 5;

Scopes may also be created with {} blocks.

{
    let a = 5;
    println(a);
}
println(a);