Today I Learned: collection of notes, tips and tricks and stuff I learn from day to day working with computers and technology as an open source contributor and product manager

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Declaring a Constant

Rust has two different types of constants which can be declared in any scope including global. Both require explicit type annotation:

  • const: An unchangeable value (the common case).
  • static: A possibly mutable variable with 'static lifetime. The static lifetime is inferred and does not have to be specified. Accessing or modifying a mutable static variable is unsafe.
// Globals are declared outside all other scopes.
static LANGUAGE: &str = "Rust";
const THRESHOLD: i32 = 10;