Natural Inference for Primitives in Flow

:::info[Historical] This post announced natural inference for primitives when it was introduced. For current behavior, see the literal types and const expressions and const type parameters documentation. :::

Flow now decides the type of string, number, and boolean literal values at their definition site: either the broad type (e.g. string) or the literal type (e.g. 'foo'). You can control the behavior with type annotations, as const, or const type parameters.

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