Conversely, a lot of languages will infer type from first assignment, so in e.g. TypeScript "let x = 5", x is inferentially typed as 'number' and the type check

Conversely, a lot of languages will infer type from first assignment, so in e.g. TypeScript "let x = 5", x is inferentially typed as 'number' and the type checker will throw if the implicit constraint is later violated. This reduces the need for explicit type annotations, clearing up a lot of the visual and cognitive noise.